Genkai is a legendary martial arts master and reiki expert whose reputation spans both the human and demon worlds. She lives alone in a sprawling temple and first meets Yusuke when she hosts a fighting tournament to find a successor for her techniques—though her real goal is to draw out the demon Rando. Yusuke wins the tournament and becomes her student, learning her signature move, the Spirit Wave Fist (or Spirit Light Wave Fist), which she trains him in relentlessly.
Despite her gruff demeanor and harsh coaching style, Genkai genuinely cares about Yusuke and the others, even if she pushes them hard to keep them on the right path. She's old and her physical and spiritual power have declined over the years, but she's still formidable and commands respect. Even after transferring most of her abilities to Yusuke, she retains enough reiki to pull her weight when needed—as fans note during the Chapter Black arc, where she proves she's far from finished as a fighter.
Content compiled by AnimeList.moe from publicly available sources.
