Ryuujirou Kotobuki

Ryuujirou Kotobuki is a junior-year student in the Mechanical Engineering department at Izu University and a vital presence within the diving club 'Peek a Boo'. Despite his rugged, muscular appearance, he carries a warm and fiercely loyal personality beneath the surface. Known for throwing wild, uninhibited drinking parties, he surprises many with his refined bartending expertise. His encyclopedic knowledge of diving and passionate dedication to the sport make him the mentor who first opened the underwater world to protagonist Iori, and he proves to be an absolutely dependable senior when the stakes are high.