Kaoru Kiyokawa transitioned from captaining the judo team at Musashi Mountain High School to joining the school's sumo club. Third-year student Goshogawara, the club's sole member desperate to compete, recruited him alongside three others: pro wrestler Takayuki Kannai, aspiring thug Nanno Ippei, and expert Go player Raiden Goro. This formed the club's foundational five-member team. Kaoru brought the physical discipline and martial skills honed in judo to bolster the group. Together, they trained rigorously and ultimately faced a professional sumo club in competition. As a main character, Kaoru is officially categorized as an athlete and sumo wrestler.