Myōsai Kakuen is an assassin affiliated with Kyosho College, a school whose fighters carry the souls of historical figures from the Three Kingdoms period. Her sole purpose is to protect and serve Moutoku Sousou, the third dragon and leader of Kyosho, to whom she owes her life. Sousou found her years earlier in a war zone in Southeast Asia, where she was nearly killed; he brought her back to Japan, and she has been utterly loyal to him ever since. She has long jet-black hair and crystal blue eyes, and she typically wears an all-white tunic with white high-heeled boots and red gloves.

Kakuen is a deadly and highly skilled fighter. She specializes in pressure point attacks that can restrain or disable opponents, and she is extremely durable, appearing to feel little to no pain. Her signature weapon is a jade shot attached to a very long metal wire, which she uses both as a projectile and for binding her enemies. Despite her ruthless demeanor in battle, she is capable of developing deep respect for worthy opponents; she gains such respect for Chou'un Shiryuu after their fight, recognizing that they both fight for someone important.

In the story of Shūgaku Tōshi Keppu-roku, which takes place immediately after the events of Xtreme Xecutor, Kakuen accompanies the Kyosho contingent during the school trip to Kyoto. She engages in skirmishes with fighters from the other Kanto schools and Kyoto’s own warriors, driven by her unwavering devotion to Sousou and her need to prove herself. She is a supporting character in this OVA, but her presence adds tension as a relentless antagonist who will stop at nothing to achieve her master’s goals. Her development across the series is minimal, as her identity remains fixed around service to Sousou, though her encounters with opponents like Chou-un hint at a capacity for growth beyond pure obedience. Her notable abilities—pressure point strikes, wire-based combat, and extreme resilience—make her a formidable foe in any confrontation.