A priest of the Holy Church and the supervisor of the 4th and 5th Holy Grail Wars. On the surface, he is a pious and cold-blooded clergyman, but internally, he harbors a distorted nature unlike anyone else. The Holy Grail War is a ritual where seven magi and seven Servants kill each other to claim the Holy Grail, which is said to grant any wish. In his youth, Kirei lived a life of faith and asceticism without understanding his own emotions. He respected his mentor, Tokiomi Tohsaka (brown hair and blue eyes), but through his conflict with Kiritsugu Emiya and witnessing countless deaths during the 4th Holy Grail War, he realized that he only feels joy in the misfortune and ruin of others. Following this realization, he murdered his mentor with the Azoth Sword gifted to him by Tokiomi and took the position of supervisor through corrupt means. Afterward, he serves as the guardian and teacher of Rin Tohsaka while managing the church in Fuyuki City. Despite his true nature, he is a devout believer in practice. During the Zero era, he has a neat appearance with bangs down, but later appears with his brown hair slightly longer and swept back. As an Executor of the Holy Church, he has mastered Bajiquan and other superior martial arts and combat techniques, possessing enough skill to overwhelm Masters even bare-handed. He considered Kiritsugu Emiya his rival, but Kiritsugu never recognized him as a special existence. Nevertheless, Kirei held a strong interest in him, and felt regret that the opponent who could entertain him was gone rather than sadness at Kiritsugu's death. Later, upon hearing the name Shirou Emiya during the 5th Holy Grail War, he shows deep interest in the fact that he is Kiritsugu's son. Kirei's true desire was not the salvation of the world, but to witness its destruction. Having become aware of his distorted nature through the Holy Grail, he seeks to confirm it endlessly without even clearly judging whether it is good or evil. He views life as a form of entertainment and finds pleasure in observing human choices and suffering. His wife, Claudia, committed suicide knowing that her husband could not love her and that Kirei loathed himself for it. She believed her death was the only way to prove he had loved her. However, even that event only served as a catalyst for Kirei to see his own nature more clearly. His hobby is eating extremely spicy Mapo Tofu.