Niji has blue-colored hair and curly eyebrows. Like all the Vinsmoke siblings, his distinctive curly eyebrows form a spiral that resemble the numeral 6. He has a similar build to his brother Ichiji, being slim with long legs and standing close to him in height. His hair is groomed into a very large, curved partition across the right side of his face, ending in three prominent spikes.
While commanding the forces of Germa 66, he wears a dark blue raid suit, including a black cape bearing a blue "2", dark goggles over his eyes, gold-colored gauntlets, and an aqua ascot around his neck. A set of horns extend upwards from his pair of orange and red earphones, and his belt bears a buckle with a prominent lightning bolt design. Outside of his raid suit, Niji wears a light-colored buttoned shirt with a tie, as well as dark pants belted with a slimmer version of the belt he wears with his Germa gear. For formal functions, he also wears a dark floor-length, single-shoulder royal cape with an upturned collar and a neck clasp.
During the Tea Party, Niji changed into a blue suit, comprised of a double-breasted jacket and pants, a baby blue cravat, and brown gloves. He also wore a white royal cape similar to the one he was wearing previously, but shorter, light-colored, and clasped together with two chains. When chaos broke out, he changed back into his raid suit.
As a child, Niji wore a light blue shirt with the number "2" on it, white pants, brown boots, a light blue bandana around his neck, and a pair of smaller goggles. His hair was styled in the same manner as it is in the present, although it was much shorter. In the anime, the bottom of his head was also shaved short as a child, creating an undercut style.
Like most members of his family, Niji is proud of his royal status, looking down upon and even abusing commoners and servants. He also expresses disgust at his brother Sanji's displays of kindness towards such individuals. Accustomed to wealth and luxury, he does not see the importance of food as Sanji does, refusing to eat a plate of aligot for what he believes to be its unappetizing appearance, and planning to discard the food into the trash.
Since birth, Niji has lacked the ability to feel empathy and sympathy due to the genetic modifications done by his father. He had no qualms about inflicting pain on servants, as shown when he attacked the head chef and even sarcastically stated that he would have avoided her face if he had known that Sanji cared for her. He is outspoken and quick to anger, as he was easily provoked by Sanji's insults, and voiced his irritation at seeing that Sanji had failed to greet him and Ichiji upon their return to the Germa Kingdom. He has also exhibited petty and vindictive behaviors, as he was willing to throw a plate at an innocent chef's face simply because Sanji defended her. Furthermore, Niji's emotional detachment is so strong that he was unmoved by even the prospect of his own death, as well as that of his family. After realizing they had been tricked, Niji remained calm, saying simply that they set their sights too high before laughing at their quandary.
While on missions, Niji is serious and business-minded, making sure to collect Germa 66's commissions after performing their mercenary services. Unlike his sister Reiju, who displayed an interest in the philosophical issue of whether war or fractured peace was preferable, Niji dismissed her musings by stating that the Germa is only ever concerned with who was willing and able to pay them the most money. Despite his own cruelty, Niji did express slight disdain for Big Mom's habits of keeping humans trapped in books, showing that he does have some small degree of moral understanding.
Like his brothers, Niji shares a lecherous streak, as he became lovestruck and drooled when he first saw Nami.Later, he expressed disappointment at the barmaids Big Mom had sent to them, and expressed a desire to negotiate for Nami's release into their custody. Despite his lecherous tendencies, however, he does have a certain degree of self-control. Unlike Yonji, he is able to overlook Charlotte Pudding's beauty and point out that marrying into the Charlotte Family would not bode well for them.
Despite his arrogance and cruel nature, Niji does have a strong sense of appreciation and gratitude, as after Sanji saved his life, Niji wasted no time in repaying Sanji by saving some of his crewmates from being killed by the Big Mom Pirates, an act that strongly contradicts his engineered apathy. This is shown again when he showed concern for his sister when Big Mom targeted her and attempted to kill her. Niji even tried going back to save her before Ichiji told him to leave her behind. Niji also didn't hesitate to rush to his father's aid after he was struck down by Big Mom. Later on, at Cacao Island, he personally escorted Sanji and Luffy to safety, narrowly saving his brother from being bombarded by a missile. While he saved his brother, he still called him a "good-for nothing" but in a joking manner.
Niji has proven himself to be extremely cunning when the situation calls for it. He imitated Nusstorte's voice after he and his siblings defeated the army of Big Mom Pirates sent after them, and completely convinced Mont-d'Or that the Germa Kingdom had been crushed.
Niji's father highly values his "beloved" second son. He approved of Niji bullying Sanji as a child, and refused to consider marrying him off to one of Big Mom's daughters even to seal a powerful political alliance. However, Niji does disregard his father's order to not injure Sanji before his wedding, as he goes on to beat him along with Ichiji and Yonji.
When the Big Mom Pirates betrayed them, Niji laughed at the fact that they fell for the trap as the family were held at gunpoint. This caused a panicking Judge to ironically state that there was something wrong with the three brothers, who were nonchalant about death.
Despite this, Niji showed concern for his father when the latter was struck by Big Mom and went back to help him. When the Whole Cake Chateau collapsed, Niji and Yonji saved their unconscious father and carried him away from the destruction.
While she was pregnant with Niji and his brothers, Niji's mother consumed a dangerous drug in an attempt to prevent him from losing his emotional capacity. However, Judge's surgery was a success on Niji, and Sora subsequently died from the drug's aftereffects during Niji's early childhood. Nothing else is known about their relationship while Sora was still alive.
As of yet, not much is known about Niji's relationship with his elder sister. Reiju was seen smiling at his return to the Germa Kingdom, implying that their relationship is friendly at the very least.
However, unbeknownst to Niji, Reiju secretly despises him along with the rest of their family (except Sanji) for their murderous ways and she intends to do nothing to stop the Big Mom Pirates from killing him, believing that there's no place in the world for any of them. Indeed, though she does pity Niji and her other two brothers for the modifications Judge made to their emotions, she still dismisses them as "barely human" even as she waits to be killed alongside them by the Charlotte Family. Later, when facing against Big Mom, Niji tried to help a targeted Reiju, before Ichiji told him to leave her behind, which Niji complied.
Niji appears to get along well with his older brother, alongside whom he has co-commanded Germa 66 forces in combat situations. Despite his confrontational behavior, Niji was compliant with Ichiji's order to pipe down after Sanji failed to greet them upon their arrival to the kingdom.
As a child, Niji, alongside Ichiji and Yonji, used to bully Sanji for his "un-royal" habit of cooking. Like his brothers, Niji took pleasure in giving Sanji a serious beating. Once during a training regimen, Niji gleefully attacked his younger brother mercilessly and only stopped when a Germa soldier held him back. When he heard that Sanji "died" in an accident, he was the only one who seemed curious over whether this was true. After finding out Sanji was alive, he continued to bully him alongside Ichiji and Yonji.
Thirteen years later, he expressed annoyance at the fact that Sanji did not greet himself and Ichiji upon their return to the Germa Kingdom. As for Sanji, he trembled slightly at their return, implying that Sanji may retain traumatic memories from their abuse.
After reuniting with Sanji, Niji mocks him by voicing his surprise at the fact that Sanji ultimately proved to be of use to their family. He also tells Sanji that, in his absence, the brothers had often speculated on the various amusing ways and place in which Sanji may have died while living on his own. While Sanji was indifferent and largely unfazed to this mockery, the two brothers did engage in a major argument immediately afterwards over their different attitudes towards food and respect for commoners. Though he does acknowledge Sanji as his brother, he was disgusted and enraged by the fact that somebody who shares his blood could be so kind to non-royalty as well eating scraps from the floor, even to the point where he's willing to attack him for it. When he was restrained by their father, Niji told Sanji he brought nothing but shame to their family as Sanji stated by being affiliated with them brought shame to him. Sanji also wanted to confront Niji for supposedly beating Cosette after he defended her from him earlier. While in the germa lab, Ichiji and Niji found Sanji and mocked him for still being pathetic despite their hopes. However, when Sanji saw Niji again, he immediately kicked him in the face, determined to make him pay for his actions and succeeded in dislocating Niji's jaw but Niji fixed his face and overpowered Sanji by using his "weakness" against him. Niji joined Ichiji and Yonji in "welcoming" Sanji back to the family before brutally beating Sanji while he laid on the floor unable to fight back because of their leverage over him.
Like his brothers, he was pleased and amused when Sanji attacked and insulted Luffy despite their friendship, as he can be seen grinning widely at Sanji's comments. However, once Sanji cried at Luffy's words, Niji simply patted on his shoulder and laughed at his anguish along with Yonji.
Niji stated he was looking forward to Sanji living with the family again after Judge explained his intent to take Pudding with them to the Germa Kingdom. Niji later joined his family in patronizingly toasting Sanji for being useful.
After the Big Mom Pirates revealed their treachery towards the Vinsmokes, Niji was dumbfounded to see Sanji save him from certain death at the wedding venue. Though he maintains a grim expression, he, along with his brothers, repaid Sanji by voluntarily saving Nami, Chopper, and Carrot from the Big Mom Pirates before retreating to Bege's castle.
Inside the castle, Niji overheard the Straw Hats stating that it was Sanji's wish to save them and showed no expression when Sanji disowned their father. He joined his family in fighting off the Big Mom Pirates to give Sanji's friends an opportunity to escape. Niji and his other siblings once again came to Sanji's aid at Cacao Island to ensure he and his captain escape. When Sanji had discovered a Raid Suit was slipped into Luffy's pocket, the cook had conjectured that the device came from Niji; Sanji had a strong antipathetic response to the consignment as he felt that it was a form of derision by Niji.
Niji's youngest brother used to accompany him and Ichiji as they bullied Sanji, showing that they at least got along. He was also excited at the prospect of a confrontational reunion between Niji, Ichiji, and Sanji. Yonji tends to laugh hysterically at Niji's various rude comments and jokes about Sanji just as he did when they were children, and on one occasion, they both share a laugh at his expense after witnessing him crying.
Niji's subordinates in Germa 66 revere him as one of their commanders, cheering him and Ichiji as they returned from their brief campaign in Broc Coli Island. As a member of their royal family, each soldier is also willing to lay down their life for Niji if commanded to do so.
Niji has no respect in the slightest for servants and commoners and seems to enjoy abusing them, as he threw a plate at Cosette's face and was furious when Sanji intervened. He also showed no remorse when telling Sanji that he was indeed the one who brutally attacked Cosette, even joking that he would beat her anywhere but her face if he knew Sanji cared for her.
Big Mom Pirates
Big Mom deceived Niji and his family in forming an alliance, but was secretly plotting to assassinate him and his family. When the Big Mom Pirates revealed their treachery at the wedding, Niji (because of his lack if emotion) remained calm in the face of imminent doom, even going as far as to laugh at falling for the trap, much to his father's fury.
After Sanji freed him, Niji fought off the Big Mom Pirates to help Sanji's friends retreat into Bege's fortress.   Niji later decided to face Big Mom along with his family to provide an opening for Luffy and Bege's groups to escape. Niji didn't hesitate to rush to confront the Yonko after his father was struck down by her. After he was overpowered, Big Mom nearly executed him but was interrupted when the Tamatebako exploded, causing the Chateau to collapse.
When the Big Mom Pirates invaded Germa, Niji and his family easily defeated them with Niji pretending to be Charlotte Nusstorte while speaking to Charlotte Mont-d'Or and divulging secret information from him. Niji and the other Vinsmokes later aided Sanji and Luffy in their escape as a way of seeking payback against the Big Mom Pirates for their deception.
Abilities and Powers
As a prince of the Germa Kingdom, Niji has political authority over its subjects, and great influence over the World Government. He also holds a high rank within Germa 66, possessing authority over common soldiers who will die for him on command. A portion of Germa 66, under Niji and Ichiji's command, was able to end a two-year war in four hours, thoroughly annihilating the side they were hired to fight.
As a member of the Vinsmoke Family, Niji also has access to the advanced technology developed by his family as well as their extravagant wealth.
He seems to be proficient at impersonation, as he tricked Charlotte Mont-d'Or into thinking he was Charlotte Nusstorte when calling him from Nusstorte's Den Den Mushi. In the anime, the hand that was holding Nusstorte appears to be glowing.
As a result of genetic enhancements, Niji possesses tremendous superhuman physical abilities. He has an outer skeleton that made him impervious to a blunt sword strike from Sanji, and one of Judge's aides said that he had developed the strength and agility of an adult man while he was a young child. One of his kicks generated enough wind force to knock a by-standing Cosette off her feet, despite Niji halting the kick in mid-air before it connected with Sanji. He was also able to throw Sanji and Luffy forward at a great speed, sending them flying through the sky over an entire fleet of the Big Mom Pirates' ships. He managed to lift Charlotte Nusstorte, an enormous man, with only one hand.
Niji possesses a tremendous amount of speed and is capable of taking down his opponents extremely quick. He was able to move so fast that Sanji, a very skilled Kenbunshoku Haki user, lost sight of him, and managed to jump a great distance to pull Sanji away from the explosion of a nearby missile before it happened. He was also able to attack several Big Mom Pirates before they could react, even while holding Sanji and Luffy, and the power of his momentum allowed him to throw Sanji and Luffy over an entire fleet.
He is also extremely durable, as he quickly fixed his broken jaw after taking a direct hit from Sanji's powerful kick and stood up to fight back almost immediately. He has a tremendous tolerance for alcohol, as he and his brothers continued to drink large quantities unaffected while the barmaids all fell intoxicated.
- Stealth (ステルス Suterusu?): Niji escapes his target's sight before quickly appearing right behind them. It was first used in his scuffle with Sanji.
Niji is highly proficient with a sword, overpowering Sanji several times in his youth. As an adult, he was shown combining his swordsmanship with his speed and Dengeki Blue ability to take out multiple Big Mom Pirates extremely quick.
- Kosoku no Ken: Henry Blazer (光速の剣
起電光剣Kōsoku no Ken: Henrī Bureizā?, literally meaning "Light Speed Sword: Electromotive Light Sword"): Imbuing his sword with electricity from Dengeki Blue, Niji speeds toward his opponents and runs in a lightning bolt-shaped motion while he strikes them down one after another. It was first used against Charlotte Oven's army on Cacao Island. This is called Lightspeed Blade: Henry Blazer in the Viz Manga.
Niji possesses an ability that has given him the name Dengeki Blue. Similar to Electro, Niji can electrify parts of his body to deal heavy damage to his opponents, and was able to knock back Charlotte Oven with a single electrified kick, successfully rescuing Chopper from his grasp. He can also imbue other objects with electricity such as a sword.
- Henry Needle (
起電ニードル Henrī Nīdoru?, literally meaning "Electromotive Needle"): Niji runs a wave of electricity through his knee and knees his opponent in the back. It was first used in his scuffle with Sanji. The henry is the unit of electrical inductance, named after American scientist Joseph Henry.
- Black Bug (
混色バグ Burakku Bagu?, literally meaning "Compound Color Bug"): A combination attack between Ichiji, Niji, and Yonji. The three utilize their abilities and hit a single target with three synchronized strikes. It was first used to break Charlotte Perospero's Candy Wall to allow Caesar Clown to escape from the Big Mom Pirates.
Niji was born as the second son and the third child of the Vinsmoke Family. At the time of his birth, the Germa Kingdom was still in North Blue. As a young child, Niji and his siblings were informed by their father that their bodies had been genetically modified, and their father instructed them to train hard in order to develop and take advantage of these superhuman enhancements. All of them succeeded in developing except for Sanji. Niji and his two other brothers were initially irritated with Sanji's poor progress, but they eventually took pleasure in bullying Sanji for his weakness as well as for feeding rats.
When Judge had Sanji locked in a dungeon and then claimed that he died in an accident, Niji wondered if Sanji had actually died. After finding Sanji, Niji and his two other brothers occasionally visited him just to continue with their bullying.
After Sanji left the family, Niji and his siblings often mused about Sanji. However, their discussions typically revolved around the numerous amusing ways that each of them could imagine as to how Sanji may have died while living on his own.
Whole Cake Island Arc
Niji and Ichiji led a platoon of Germa 66 soldiers to end a two-year war on Broc Coli Island. They did so in four hours, and Niji collected the payment for their services from the winning side. Niji and Ichiji then stood on a rooftop to observe the burning country, as they arranged to make the two day journey to Whole Cake Island. While Ichiji expressed excitement at seeing Sanji again, Niji called him a liar.
Two days later, Niji and Ichiji arrived at the Germa Kingdom. As they received a hero's welcome from the Germa 66 soldiers, Niji was annoyed that Sanji was not there to greet them, but was told by Ichiji to quiet down.
Sometime later, Niji was having a meal with his father and siblings. After a discussion with his father about the Levely, Niji stated that he thought he would never see the day Sanji would be useful. Niji told Sanji that when he left the family, he and the other Vinsmoke brothers all spoke about him but their conversations revolved around the amusing ways and place he'd most likely to die. Sanji ignored this and proceeded to tell Niji to finish what was on his plate, but Niji refused and was irritated when Sanji called him a spoiled prince who does not know the value of food. Niji then angrily called the head chef, Cosette, and threw his plate at her. Sanji caught the plate and scorned Niji for trying to hurt a woman. As Sanji ate the food that fell on the floor, Niji was disgusted at this. Niji attempted to kick Sanji, but their father quickly stopped him. Niji told Sanji he brought shame to their family, but Sanji stated being affiliated with them is shameful to him. As their father coerced Sanji by threatening Zeff's life, Niji and his siblings exited the dining hall, and Niji severely beat Cosette in retaliation for Sanji's actions.
Niji and Ichiji later met Sanji and Yonji in the Germa lab, where they mocked Sanji for still being pathetic. Seeing Niji again, Sanji immediately kicked Niji's face in anger over what he did to Cosette. Niji's jaw was broken, but he fixed it with his hands and quickly got back up and beat Sanji into the ground when Ichji reminded Sanji of Zeff. While Sanji was lying on the floor, Niji mocked him for his values.  After injuring Sanji further, Niji left the lab with Ichiji and Yonji.
Niji later departed the Germa Kingdom with his father and siblings and headed for Big Mom's castle in his family's carriage. On the way, they encountered Luffy and Nami. Upon seeing Nami, Niji gazed at her in a love-struck manner. When Sanji coldly turned down Luffy's request to return with him, Niji smiled.
Niji watched with amusement as Sanji continued to reject Luffy and Nami and then severely beat Luffy by repeatedly kicking him. After knocking Luffy down, Sanji returned to the carriage and the Vinsmoke Family continued on to the Whole Cake Chateau. When Luffy declared that he would wait for Sanji, Niji laughed alongside Yonji.
As the carriage approached Big Mom's castle, Niji expressed amusement at watching an army marching towards Luffy and Nami's location. After arriving at the castle, Niji and his family had a meal with Big Mom and Pudding.
Sometime after the lunch meeting, Big Mom took the Vinsmoke Family (except Sanji) to her library and showed them her collection of rare creatures stored in books.
Sometime after the tour, Niji, Judge, Ichiji, and Yonji had a private discussion in the Vinsmoke guest room. Judge told his sons that Pudding would be living with them on Germa Kingdom after the wedding so they could use her as leverage against Big Mom. When Niji asked if Big Mom would use a similar tactic, Ichiji told Niji that it would not have any effect on the Vinsmoke Family if Sanji's life was threatened. Niji then expressed excitement at the thought of Sanji living with them again.
During the night before the wedding ceremony, Niji, Ichiji, Yonji, and Judge celebrated the anticipated sealing of their alliance with Big Mom. While they drank, they toasted to Sanji for being useful.
On the day of the wedding ceremony, Niji was shown getting dressed for the wedding, alongside his father and elder brother. As Judge and Ichiji inquired about Reiju's location, Niji went to wake Yonji up and told him to get prepared for the Tea Party. An hour later, the Vinsmokes headed to the ceremony venue on the roof of the Whole Cake Chateau. As they made their way through the castle, Niji told off Yonji for questioning Reiju about her whereabouts on the night before. After Niji asked if Sanji tried to escape, the Vinsmokes received confirmation from one of Big Mom's subordinates that Sanji was ready for the ceremony.
After the tea party began, Niji spoke to Charlotte Galette and another female guest. After Sanji and Pudding arrived at the venue, the Vinsmokes took their seats and watched the exchange of vows. Yonji commented that he would not mind marrying a beautiful woman like Pudding, but Niji and Ichiji reminded him on what it means to marry one of Big Mom's children.
After Brook destroyed the picture of Carmel, the Vinsmoke Family found themselves restrained to their seats with members of the Charlotte Family holding them at gunpoint. As Judge cried out in anguish at Big Mom's betrayal, Niji casually commented on how they were tricked and started laughing in amusement, with him and his brothers not caring about death due to their lack of emotions. Moments later, as Big Mom began to scream, Niji managed to stay conscious as his family's captors began falling all around them. Sanji then arrived and freed him by shattering the hardened candy around his body while Nami gave him back his raid suit.
As the Charlotte Family resumed their efforts to kill the Vinsmoke Family, Niji and his siblings put on their raid suits. Niji then rescued Chopper by kicking away Charlotte Oven, before retreating into Bege's fortress.
As Bege's fortress was suffering damage from Big Mom's attacks, the Vinsmoke Family decided to fight Big Mom in order to give the alliance an opening to escape. After exiting Bege, Niji blocked a volley of bullets fired by the Big Mom Pirates. After Reiju took an attack from Big Mom, Niji showed concern but Ichiji told him to remain focused on the mission.
In the ensuing confrontation against the Big Mom Pirates, Perospero attempted to use candy wall to block Caesar as he was carrying Bege and everyone inside him. Niji, Ichiji, and Yonji combined their attacks to destroy the candy wall, allowing Caesar to pass through. When Judge went down after clashing with Big Mom, Niji and Yonji then rushed towards their father's aid, but they were soon overwhelmed and caught by Big Mom herself. However, before she can execute them, the Tamatebako dropped to the base of the Whole Cake Chateau and the bomb inside the chest exploded, causing the entire castle to collapse. As the castle fall, Niji and Yonji carried their father to safety.
Back at the Germa Kingdom, the Vinsmoke siblings defeated the pursuit team that went after them. Niji then contacted Mont-d'Or through a Den Den Mushi and impersonated one of the Big Mom Pirates, tricking him into thinking that Germa 66 was crushed. After hearing about the direction the Straw Hats were heading, Ichiji told his siblings to set sail.
When Luffy and Sanji were cornered by the Big Mom Pirates at Cacao Island, Germa 66 arrived just in time to assist them. Their interference allowed Sanji and Luffy to escape, but the duo were quickly attacked again, and one enemy pirate shot a missile at them. Niji jumped up and pulled them away from the explosion, rocketing toward the coast as he cut down several pirates with his sword. Before throwing Sanji and Luffy toward the Thousand Sunny, Niji secretly gave Sanji a raid suit.
As the battle raged on, the Big Mom Pirates brought anti-Germa bullets and used them to injure Niji and his siblings. Despite those injuries, Niji kept fighting. When the Straw Hats finally escaped Totto Land, Germa 66 prepared to withdraw. However, Big Mom arrived at Cacao Island before they could retreat.
- Ichiji, Niji, and Yonji vs. Sanji
- Niji vs. Sanji (Germa Kingdom training ground)
- Niji vs. Sanji (inside Germa Lab)
- Sanji Retrieval Team-Fire Tank Alliance vs. Big Mom Pirates
- Vinsmoke Family vs. Charlotte Nusstorte and his pursuit squad
- Germa 66 vs. Big Mom Pirates (Cacao Island)
- Niji, Ichiji, Yonji, and Reiju vs. Germa soldiers
- Niji vs. Charlotte Decuplets (Whole Cake Chateau)
- Niji vs. High-Fat and Charlotte Noisette
- Niji vs. Charlotte Daifuku
- Niji vs. Charlotte Nusstorte (Germa Kingdom)
- Niji vs. Charlotte Raisin
Early One Piece
- In keeping with the Vinsmoke Family's naming convention, Ni (二) means "two" in Japanese. This is a reference to Niji's position as the family's second-born son, despite being the third-born child.
- In the Marine comic strip, Sora, Warrior of the Sea, there is a brief scene of Sora facing Germa 66. On Germa's side are three cloaked agents, one of whose cloaks bears the number "2"; the figure is likely a representation of Niji.
- Niji's callous disregard of food and women are in total contrast to his younger brother Sanji's values, who values both.
- Niji's fighting style is different from his brothers. While Ichiji and Yonji mainly rely on punches and powers from their hands, Niji uses kicks and a sword instead.
- Coincidentally, his fighting style is similar to Sanji as they are both very agile and primarily use kicks in battles.
- Niji's attack known as Henry Needle referenced to a henry, which is the unit of electrical inductance, named after American scientist Joseph Henry.
- He was ranked 93rd in the sixth popularity poll.