Amidamaru is a six-hundred-year-old samurai ghost who serves as the primary spirit ally of Yoh Asakura, the protagonist of Shaman King. He was born on January 6, 1385, during the Muromachi period in feudal Japan and died at the age of twenty-four. Orphaned at a young age, he grew up protecting other orphaned children, which forged his skills as a warrior. His best friend was Mosuke, the son of a swordsmith. Because Amidamaru could only afford poor-quality steel and refused to steal swords from the dead, his katanas often broke. Moved by this, Mosuke used his late father’s hunting knives to forge an exceptional katana. Touched by the sacrifice, Amidamaru shed a tear, and pretending it was rain, named the sword Harusame, meaning Spring Rain. As adults, both were employed by a feudal lord who was impressed by their talents. But the lord, motivated by greed, ordered Amidamaru to kill Mosuke to prevent him from ever forging a superior blade. Torn between duty and friendship, Amidamaru revealed the truth to Mosuke on Funbari Hill and urged him to flee. Mosuke asked to take Harusame to reforge it and promised to return the next night. A spy overheard their plan, and the lord sent men to kill them both. Amidamaru fought without Harusame and died from exhaustion. Mosuke arrived too late with the perfected sword and died soon after, his spirit lingering within Harusame. Amidamaru’s spirit remained on Funbari Hill for six hundred years, bound by his oath to wait for Mosuke, earning a fearsome reputation as an infamous killer. In the present, a local delinquent named Wooden Sword Ryu broke Amidamaru’s tombstone. Yoh Asakura, seeking to avenge his friend Manta Oyamada, revealed his power and asked for Amidamaru’s help. Using Spirit Integration, Yoh merged with the samurai’s ghost and defeated Ryu. Yoh then asked Amidamaru to become his permanent guardian ghost, but he refused because of his oath. After Yoh and Manta learned the truth of his past, Yoh retrieved and repaired Harusame and returned it on Funbari Hill with a message from Mosuke. With his oath fulfilled, Amidamaru accepted Yoh’s offer and became his faithful spirit ally. Amidamaru is taciturn, loyal, and extremely devoted, addressing Yoh as Yoh-dono, meaning Master Yoh. Despite his fearsome reputation, he has a warm heart and deeply cares for his friends. He has expressed quiet anxiety about being unable to become stronger because he is a ghost. Key relationships include his profound bond with Mosuke, a friendly rivalry with the bandit Tokageroh (whom he killed in life), and a close partnership with Yoh. At the conclusion of the main series, Amidamaru becomes the guardian ghost of Yoh and Anna Kyoyama’s son, Hana Asakura. As a combatant, he possesses remarkable visual acuity and masterful swordsmanship. He can change his form as a ghost and uses techniques such as Spirit Integration and the Oversoul with Harusame as a medium. His signature moves include the Amida-Ryu: Shinku Budda Giri, a vacuum slash, and the Amida-Ryu: Gokojin, a devastating dual-sword battōjutsu performed from his legendary fighting stance known as Nyorai.