Yoriichi Type Zero

Yoriichi Type Zero is a combat doll constructed by ancestors of the swordsmith Kotetsu during the Sengoku period. Craftsmen from the Swordsmith Village assembled it as a training tool for Demon Slayers, basing its design on Yoriichi Tsugikuni, the founder of the Breathing Styles. Two arms proved far too few to mimic his speed, so the makers fitted it with six, each gripping a katana.

Across the roughly three centuries it has existed, the doll has worn down considerably, with a half-cracked head and battered arms. Its six arms and the placement of their joints evoke the Asuras of Buddhist tradition, and its programmed total of 108 movements echoes a number held sacred across Dharmic religions and many East Asian martial arts.

The doll holds 108 distinct movements modeled on Yoriichi, and its power exceeds that of most humans, which is why it serves as a training dummy. Centuries of erosion have left it far weaker than it once was. It can be tuned to target an opponent's weaknesses by rotating its fingers and adjusting settings inside its head, though Kotetsu deliberately disabled these refinements when Muichiro forced his way to a session.

As a stand-in for the strongest Slayer in history, the doll executes highly skilled swordplay even though it cannot think or draw on Breathing Styles. Even degraded by age and set to a weaker mode, it matched the gifted Muichiro Tokito, and at a higher difficulty it bested Tanjiro Kamado, who needed days of effort before he could defeat it. A katana more than three centuries old was sealed inside its body and revealed only when Tanjiro finally struck its neck.

Demon Slayers train against the doll. Kotetsu, its young swordsmith owner, maintains and later repairs it, while Muichiro Tokito and Tanjiro Kamado both use it during the Swordsmith Village arc, Tanjiro spending many grueling days before landing a decisive blow. The doll debuts in Chapter 102 of the manga and appears across Episodes 45 and 46 of the anime, and it joins the roster as a playable fighter in The Hinokami Chronicles 2.