Based on available details, Issei Ryudo appears as a minor character in "Fate/kaleid liner PRISMA☆ILLYA", holding the role of Student Council President and being a friend to Shirou Emiya, mirroring his role in "Fate/stay night". He is the son of the head priest of Ryuudou Temple and possesses a serious personality marked by distrust toward Rin Tohsaka. One noted appearance occurs during a beach party where he assists Shirou Emiya, displays observant behavior regarding Rin Tohsaka and Luvia Edelfelt, and comments that Shirou's care would be best handled by someone from Ryuudou Temple.