The story of Tsubasa to Hotaru revolves around Tsubasa Sonokawa, a 15-year-old student who is rumoured to be a stalker. When a popular senior makes a grand romantic gesture, Tsubasa falls head over heels for him, believing him to be the one for her. Unfortunately, her love is unrequited, and the senior bluntly tells her to stop bothering him. This heartbreak hits Tsubasa hard. Coincidentally, Tsubasa’s friend Yuri gets injured, leaving her unable to continue as the basketball team's manager. Tsubasa takes up the role at Yuri's request, hoping to move on from her failed love pursuit. On her first day, she is almost hit by a stray ball but is saved by Aki Hidaka, the team's shooting guard. Is this just a lucky coincidence, or another fateful encounter? One thing is for sure, her life is about to change.