Genkai won the Dark tournament 50 years ago. She wished to never be bothered with the committee again but her apprentice, Yusuke Urameshi had to enter or everyone he know would die. Genkai entered as the fifth member of his team, calling herself the masked fighter. But she was killed by Toguro before the finals of the Dark Tournament. Toguro and Genkai had been on the same team on the previous tournament 50 years ago, supposedly they had been lovers. Toguro had wished to become the strongest demon and to not age, that ended their relationship. Genkai was brought back to life by Koenma once Yusuke and his team had won the tournament.

She is a very strict old woman. She calls Yusuke “dimwit” on a regular basis, but she does care about him. She believes that you shouldn’t run away from time and wants Yusuke to not run away either. When Genkai uses the Spirit Wave she changes back to her youth for awhile.