Kōtarō Watari is a second-year student at Sōshūkan Private High School, also known as Ao High, and a member of the school's boys' rhythmic gymnastics team. He was born in Miyagi Prefecture. His family runs a ramen shop, which has given him advanced cooking skills. Despite his sharp eyes and pierced ears, which often cause strangers to misjudge him as intimidating, Watari has a kind and good-natured personality. He is known for being attentive and caring toward his juniors, looking after them both in and out of practice. He also has a tendency to come up with odd nicknames for others. As a supporting member of the team, Watari contributes to the group's dynamic as an upperclassman, helping the younger members settle in and supporting the team's shared goal of reaching the Inter-High competition. His role is primarily that of a reliable teammate and a gentle presence within the club. Over the course of the story, he grows alongside his teammates, developing stronger bonds and a deeper commitment to rhythmic gymnastics. Notable abilities include his culinary talent and the rhythmic gymnastics skills he has built as a regular member of the squad.