Genkai, a legendary martial artist and psychic mentor, mastered spirit energy and forged advanced techniques. A seasoned warrior, she orchestrated a grueling tournament to identify a worthy heir, testing candidates' spiritual strength, adaptability, and survival instincts through rigged arcade games measuring precognition, a demon-infested forest trial, and lethal combat rounds. Yusuke Urameshi earned her legacy by defeating Rando, a demon infiltrator seeking to steal her secrets.

Her past intertwined with Younger Toguro, a former ally during an earlier Dark Tournament victory. Their partnership shattered when Toguro embraced demonhood, while she retreated to the human world. Decades later, she reentered the Dark Tournament disguised as a masked fighter, channeling her prime spiritual energy to temporarily regain youth—a testament to her Spirit Wave technique’s extremes.

Sacrificing her remaining power to empower Yusuke against Toguro, she fell in battle but was revived via a wish from Team Urameshi’s tournament victory. Resuming her role as mentor, she honed Yusuke’s skills for the Makai Tournament, employing unorthodox methods like spirit cuffs to enforce continuous energy control and temper overconfidence.

Her arsenal featured the Spirit Wave Orb, a condensed energy sphere inherited by Yusuke, and Spirit Reflection Blasts to redirect enemy attacks. Healing and purification techniques like Spirit Wave Purification targeted those with inherent goodness. Despite aging, her combat fusion of martial arts and energy manipulation rivaled high-tier demons.

In later conflicts, she guided Yusuke through struggles with his demon lineage, offering pragmatic counsel. The manga concluded her arc with a quiet passing, her estate entrusted to Yusuke and allies. The anime expanded her influence, depicting ongoing mentorship and involvement in the Makai Tournament’s aftermath.