Rai Aguni is a mystic master and the official protector of the World President. He once instructed both Genichirou Izayoi and Rebi Ra in spiritual and martial arts, including the chi-manipulating Nempo discipline and swordsmanship.

After Rebi Ra's betrayal and acquisition of demonic power, Rai Aguni became the primary guardian of the World President. A strategic attack by Rebi Ra struck the president with a demonic curse, intentionally immobilizing Rai Aguni. The mystic was forced to channel his magic continuously to sustain the president's life, preventing him from confronting the threat directly.

This situation led Rai Aguni to seek outside help. Using astral projection, he located and communicated with Kyoya Izayoi, the son of his deceased student Genichirou. He revealed the history between his two students and charged Kyoya with the mission to enter demon-infested Shinjuku and defeat Rebi Ra, as he was considered the only one capable of stopping the sorcerer.

His role is bound by duty to protect the world's leadership and his strategic response to a crisis that incapacitated him, leading him to delegate a critical mission to a new generation.