Sorata Tsuwabuki is Keita's youngest brother and sibling in the Binbogami Ga! franchise.
Ryuuta Tsuwabuki is created by Yoshiaki Sukeno in the Binbogami Ga! manga series. He has no information regarding any inspiration used by Yoshiaki Sukeno for his creation. He makes his first manga debut in volume 1: chapter 2 and first anime debut in episode 3.