Genkai (幻海?) is an elderly martial arts expert who lives alone in a very large temple. She first appears during Yusuke's second case as he infiltrates a tournament she is holding to find a successor to her techniques in search of the demon Rando. Genkai is a legendary reiki master, known both in the human and demon realms. Yusuke ends up winning the tournament, defeating Rando in the process, and is taken on as a student by Genkai. When she was 50 years younger, Genkai and the younger Toguro brother were lovers and teammates in an earlier Dark Tournament. After winning, Toguro decides to become a demon, while Genkai returns to the human world, creating a split in their relationship. She enters the next Dark Tournament with Yusuke, disguising herself as the "Masked Fighter" in order to once again face Toguro. Genkai was killed during the tournament after a powerful blow from Toguro the day before the finals, and was subsequently brought back after the competition ended. Her signature technique is the Spirit Wave, an outpouring of spirit energy from the whole body which can be directed through several different variations. This makes her technique effective in healing and purification, in addition to combat. A side effect of using this power is a shifting of the body's cells which leads to a temporary reversion to the form in which the wielder was at their most powerful in life. In Genkai's case, it allowed her to briefly regain her youth. At the end of the manga, Genkai dies, leaving her vast land to Yusuke and his friends. In the anime television series, Genkai is voiced by Hisako Kyōda (Older) and Megumi Hayashibara (Younger) in Japanese and Linda Young in English.