The Shichiseiken is considered to be the world's most beautiful sword and a valuable treasure, despite its cursed legends. The sword is designed after a Shuangshou Jian, a two handed double edged sword and the bigger cousin of the Jian, with an eight-petaled design guard and a somewhat elaborate hilt and a red tassel at the end. The blade itself is emerald green, with a wavy design and seven glowing points spread evenly across it; these design glow green when the blade is active.
The Shichiseiken is a powerful blade that has been cursed by the bloodshed of its creation. It grants immense power to its wielder, and heals any wounds on the user, such as Saga's crippled arm, but corrupts their mind and conquers them. The cursed blade can drain blood to strengthen itself and the wielder, and produce greenish flames. It is also quoted that even if the bearer is not naturally a swordsman, he will gain an excellent sword-handling ability, a very own version of Ittoryu. However those under its influence could not touch the jewel orbs.
The blade is highly durable as Zoro's Yaki Onigiri did not even leave a mark on it, Zoro himself states that his attack was supposed to destroy the Shichiseiken. It can also merge with its wielder, giving them the ability to cut objects with their bare hands at any range, becoming nigh unstoppable; even if the blade is destroyed, the curse can remain in the host.
While Saga was wielding the Sword, he showed off two attacks.
- Yokazan (妖火斬 Yōkazan?, literally meaning "Cursed/Mystic Fire Slash"): Saga scrapes the sword at the ground, and the friction creates a green-colored flaming projectile that he launches at the opponent. Sword thrusts can also hurl the flame as explosive fireballs for ranged attacks.
- Yoja: Gashuzan (妖蛇・牙襲斬 Yōja: Gashūzan?, literally meaning "Cursed/Mystic Snake: Fang Assault Slash"): Saga transforms the Seven Stars Sword into a blue-flame snake and attacks with it, in which the snake bites the opponent several times and drains a large amount of blood.
- Shockwave Projection: Similar to the Gura Gura no Mi, once upon reaching the fullness of its power The Shichiseiken's swings can project vorpal shockwaves which can wound even a rubber man. After full possession of its host, the evil spirit allows Saga to project even stronger vorpal pressure blasts wit a sweep of the hand.
Creation and Revival
The Shichiseiken was a sword created by the God of Asuka for the king of the land as a holy weapon to protect his people. However, the three princes' relationship become strained as they tried to win the heart of a maiden by means of taking the sword as their own gift to the girl. Embroiling themselves in a bloody war that consumed the entire nation, the once sacred sword absorbed all the negative energy around the bloodshed. The maiden sacrificed her life to stop the warring kingdom and, in their sorrow, the princes sealed the sword using three orbs given by the same god.
Years later, Saga found the sword in a crypt during a pirate attack. He and his fiancée, Maya, were cornered in and Saga used it out of desperation to save her. However, the sword's evil influence possessed Saga and brainwashed him into trying to rise to full power, using its power to possess a nearby Marine dojo to do its bidding.
Encounter with the Straw Hats and Destruction
One year later, sensing his old friend Roronoa Zoro nearby, the possessed Saga contacts him for its plans to get rid of sacred jewels that could seal its evil power. However, Monkey D. Luffy manages to find these jewels and the Straw Hat Pirates, with the help of Maya, are able to enact a ritual that will suppress it power. The sword tries to stop this and nearly succeeds.
The Sword was initially defeated by Luffy, but then merges with Saga's body, making it near unstoppable. It was even able to disperse Maya's barrier on its own. However, it was finally stopped when Zoro appears and calls to Saga's consciousness, challenging him to a sword duel. Zoro manages to slash at Saga but only destroys the sword's influence, allowing Saga to live.
- Chinese swords of the Tang dynasty often bore the mark of seven stars, the Big Dipper constellation, on their blade and are referred to as seven-star swords. This is further supported as the Seven Stars Sword's design is based on a Chinese sword.
- The Shichiseiken is based on a tool from the Chinese classic "Journey to the West". In this story; there are two demon king brothers, known as the Great King Kinkaku and the Great King Ginkaku. The siblings possess five treasured tools, one of which is called the Seven Star Sword.
- The Shichiseiken also has connections to Taoism. Seven Stars (七星 Shichisei?) is the name given to the seven brightest stars of the constellation Ursa Major (which actually form the Big Dipper constellation) in China and Japan. Swords based on Taoist thought and bearing this name are said to hold the power to crush evil and protect.