Futsu

A dark yellow vest worn over a black tank top forms Futsu's combat outfit, finished with grey trousers and pale sleeves that cover his forearms. His dark brown hair is shaved close along both sides and gathered at the back into a small ponytail. He has a youthful, light complexion, and his green eyes lack any visible pupils.

En Oyashiro rates Futsu as the finest fighter under his control, and that confidence rests on a formidable bloodline trait. Through the Boil Release kekkei genkai, Futsu fuses fire and water chakra at once to conjure an eroding vapour that eats away at whatever it touches. The technique makes him dangerous at a distance, letting the corrosive mist inflict the damage his opponents struggle to avoid.

Futsu's story unfolds in Sasuke Shinden: Book of Sunrise. Oyashiro sets him against Sasuke Uchiha inside the Coliseum, gambling that a victory will hand him ownership of the Uchiha. Sasuke, who once contended with Mei Terumī and her own boil-based abilities, reads the mist with ease and ends the bout using the Great Fireball Technique.

Winning entitles Sasuke to claim Futsu as property, but he refuses the prize and asks only for an audience with Oyashiro. That conversation persuades Sasuke to intervene on behalf of the arena's captives, so he demands a second match against a now-healed Futsu. Beating him again, Sasuke turns the outcome into a release, granting him his freedom. The novel has Sasuke enlist Yamato to resettle the liberated slaves in Konoha, while the anime places them in Kumo's care instead.