Issei Ryuudou (柳洞 一成, Ryūdō Issei?) is a supporting character in Fate/stay night. He is the Student Council President of Homurahara Academy.

He has a straight-laced and serious personality. As the youngest child of Ryuudou Temple, it seems he has his heart set on one day becoming a Buddhist monk. Though, he will be the first to tell you that his ability to sense the supernatural is weak. He looked up to Souichirou Kuzuki as a mentor, and on holidays they would often perform paired kata together. If he had not gone into the student council, it's a safe bet that he would have enrolled in the karate club instead.[2]

Issei is a friend of Shirou, and his favorite dishes are the lunches that Shirou makes.[2] Issei often asks Shirou to fix broken equipment for the Student Body to try and save money on the school's bill. Issei and Shirou often have lunch together in the Student Body's office where they talk about what ever comes to mind.