Akari Ōshiro is a first-year student who becomes a key member of the beach volleyball club at Uruma High School. Her initial motivation for approaching the sport is not rooted in a lifelong passion for athletics but rather a desire for recognition. Inspired by a photo magazine featuring the popular and successful pair Narumi Toi and Ayasa Tachibana, Akari dreams of becoming a beach volleyball idol and gaining popularity. However, her aspirations shift upon joining the team. After failing to recruit a partner from the existing members, she initially decides against joining, but a challenge from Kanata Higa leads her to reconsider. Ultimately, she becomes the club manager, a role that solidifies the club's official status as it provides the necessary fifth member.

Akari possesses a tsundere personality, often becoming flustered, embarrassed, or nervous, particularly when others express friendship towards her or use her embarrassing nickname, Shii-Chan. This nickname, much to her chagrin, is a remnant of her past as a child actress in a local beverage commercial, where she was known as the Shequasar Girl. Despite her rookie status in volleyball, being even less experienced than the protagonist Haruka Ozora, Akari is hardworking and dedicated. She actively participates in training drills with the rest of the team, demonstrating a commitment that goes beyond a simple managerial role.

Akari's key relationships are primarily with the other members of the Uruma High Beach Volleyball Club, including Haruka, Kanata, and the Thomas twins, Claire and Emily. Her addition to the group is crucial, as it fulfills the minimum membership requirement, allowing the club to be officially recognized. She has a particularly memorable interaction with Marissa Thomas, the twins' mother and a former professional player, whom Akari comes to admire greatly, especially for her perfect physique. In a gesture symbolizing the unity and friendship of the club, despite its members being rivals on the court, Akari gives each of them a hibiscus scrunchy.

While not a star player, Akari contributes notable abilities to the team. Her most significant asset is her high endurance and stamina, which she credits to her past training and experience as an idol. This physical resilience allows her to keep up with drills and support the team effectively. Over the course of the story, her character develops from a fame-seeking newcomer into a reliable manager and a genuine friend who takes pride in her role supporting the team, ultimately finding more value in the connections she makes than in the pursuit of popularity.