Akanagi High School is a school with powerhouse boys' and girls' basketball teams that compete at the national level every year. It is also a school that forbids romantic relations between the male and female members of the teams.

Among the second-years is "Reika Hashimoto" who is the ace of the girls' team and she's secretly dating her childhood friend "Yuuji Fujimoto" from the boys' team.

Fujimoto has a close friend named "Tanaka" who's still a benchwarmer. He stays with him everyday after school for practice, aiming to become a regular. However, that day Fujimoto had to go to cram school and so their practice got cut short...

Tanaka was preparing to go home from practicing only after the last person leaves, when a smartphone left behind by someone began ringing. Intending to return it to the owner, he accessed the contents to check the identity, only to realize that it was Fujimoto's phone and this leads him to finding out about Fujimoto and Hashimoto's secret...

While Fujimoto is away at cram school, Tanaka goes on a mission to exploit the secret on his friend's phone...!!