Koyuki's guitar and swimming teacher, Saitou once swam in the Olympics but was unable to achieve his dream of winning so has turned his life to teaching others how to swim better. Saitou is loud and demanding in public, and especially strict when it comes to swimming. But when he is out of the water he is much more open, even turning to Koyuki for advice on his attractions to Momo. Saitou is a fan of British rock and his favorite band in the anime is the fictional Rocket Boys