It is the month when everyone in Wano Country are filled with cheers and happiness, or at least that is what is supposed to be.
Long ago on every Christmas Eve, the benevolent Kozuki Oden would deliver presents to every citizen, spreading joy throughout Wano. However, there was one cruel man known as Kurozumi Orochi, who was filled with so much greed that he was never satisfied with what he was given. He wanted to be the only one in Wano who would receive all the presents.
Before Christmas Eve twenty years ago, on the nearby island of Onigashima, Orochi performed a dark ritual and summoned the dragon of despair, Kaido. Impressed with Orochi's black heart and willing to entertain the idea of bringing misery to Wano, Kaido formed a pact with Orochi.
Backed by Kaido and his army of beast warriors, Orochi quickly took over Wano Country. He captured Oden and executed him in front of his people. Kaido also trapped Oden's family inside Oden Castle before setting it ablaze. Oden's wife, Toki, performed a spell to send her son, Momonosuke, and his retainers Kin'emon, Kanjuro, and Raizo to the future. Before she was consumed by the flames, Toki declared that Orochi's reign will end twenty years later.
Twenty years later on the first day of December, Momonosuke and his retainers returned. They soon discovered how much Wano changed over the years. It became a dark and gloomy country and ever since the fall of the Kozuki Family, the people were enslaved and Orochi was the only one in Wano to be happy. Seeing that the people were too afraid to stand up to Orochi and Kaido and learning that Kaido cannot be destroyed, the Kozuki Family decided to find help at Zou, home of the Mink Tribe that are long time friends of Oden. Momonosuke and his retainers then stole a boat and left Wano, but they were spotted by the beast warriors.
After a long journey, the Kozuki Family finally arrived at Zou. The minks' leaders, Inuarashi and Nekomamushi, warmly welcomed them. They then escorted the family to a secret chamber. Inuarashi then presented Momonosuke a magic scroll that would enable him to summon champions who could aid in his cause. With the scroll, Momonosuke summoned the Monster Trio: Luffy, a man with a body of rubber; Zoro, a swordsman with the strength of a demon; and Sanji, a man with legs that are mightier than iron and can incinerate anything they touch. Momonosuke humbly asked the Monster Trio to help him. Luffy agreed to help in exchange for meat. Zoro wanted sake. And Sanji just wanted to find love.
A terrifying force that had been following the Kozuki Family arrived at Zou. A mammoth of destruction and one of Kaido's three lieutenants, Jack, lead an army to eradicate the Kozuki Family. The Mink Tribe tried to fight back, but Jack was too powerful. The Monster Trio then stepped in and with their combined strength, they destroyed Jack and the invasion force. As the Kozuki Family prepared to journey back to Wano with the Monster Trio and Mink Tribe, Nekomamushi gave Momonosuke a magic scroll that would enable him to banish Kaido.
On the day before Christmas Eve, the Kozuki Family returned to Wano with their new allies. They quickly eliminated all the beast warriors stationed in Wano and liberated all the slaves and prisoners, giving hope to the people for the first time in years while also forcing Orochi to retreat to Onigashima. With Wano's warriors rallied behind them, the Kozuki Family then set their sights on Onigashima, the island where Orochi and Kaido resided.
On Christmas Eve, the Kozuki Family and their allies stormed Onigashima and fought against Kaido's army. The Monster Trio passed through the army like it was nothing. Once the Monster Trio had gone close to Orochi's stronghold, Kaido's remaining two lieutenants, King and Queen, confronted them. Luffy went ahead while Zoro and Sanji fought these two powerful foes. Inside the stronghold, Luffy crushed any enemy that crossed his path until he reached Kaido's chamber. Back outside, Zoro and Sanji battled fiercely against their opponents, causing major destruction to their surroundings. Pushed to the limit, Zoro and Sanji revealed their hidden power and triumphed over King and Queen, but were left too exhausted to continue the fight, leaving Luffy to face Kaido.
Inside Kaido's chamber, Luffy declared that he would defeat Kaido and made the first strike. Luffy and Kaido then engaged in a gruesome destructive battle that devastated the fortress until they took their fight outside. The two traded blows but even at his strongest, none of Luffy's attacks were able to harm Kaido. The dragon continued to overpower Luffy and the latter was on the brick of defeat. Though the battle was in Kaido's favor, the people of Wano cheered for Luffy. Suddenly, Luffy felt a surge of power flowing through him. Empowered by the people's Christmas spirit, Luffy turned the tables on Kaido and unleashed a powerful attack that completely incapacitated the dragon, finally ending the battle.
With his ally beaten, Orochi attempted to flee but Momonosuke's retainers caught him. With the scroll Nekomamushi gave to him, Momonosuke banished Orochi and Kaido to the netherworld. With the their master gone, all the remaining beast warriors faded away.
Now that Orochi's oppression and the terror of Kaido came to an end, the people of Wano celebrated and declared the downfall of Orochi as their Christmas miracle. Momonosuke began following in his father's footsteps of spreading joy throughout Wano and the Kozuki Family, the Mink Tribe, and the Monster Trio all celebrated Christmas together.