Genkai

幻海

She trains Yusuke in the Spirit Light Wave Fist (Reikou Hadou Ken), known as the Spirit Wave in the English dub, and pushes him to his limits. Although she may seem harsh toward Yusuke and the others, she genuinely cares for them all and strives to guide them in the right direction.
Genkai 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 hosting to find a successor for her techniques while searching for the demon Rando. Genkai is a legendary reiki master, renowned in both 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.

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Although Genkai is of advanced age and her physical and spiritual strength has declined, she remains a fighter to be respected and feared. Even after she gave up most of her power to Yusuke, she is still capable of using some Reiki, notably during the Chapter Black saga.

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