Ryuutarou is Rizumu's father, and also Sonata Amamiya's husband. He once wanted to become a superstar, reflected in his current attire, but because of Sonata's rising success, he had to quit. He became a home-maker instead. He is still very hurt by Sonata's leaving the house when the story begins, and protected his daughter at all costs to make sure the same trauma does not happen to her.