Kouji Takahashi, who admires Manatsu (Manatsu), the head of the women's swimming club, calls her one day and is surprised and confused by the sudden confession of his feelings, but he is struck by his desperation and decides to go out with him... The two were enjoying their happy student life, but their classmate Tatsuya Arakawa was dissatisfied with their appearance. And he fell for Arakawa's trick... Manazu called Arakawa to save her boyfriend, but on the contrary, she found out that she was holding evidence of her boyfriend's weakness. With the sole desire to protect her boyfriend, with Arakawa... He signed a contract. And the last summer of their student life begins...

The contract with Arakawa was still going on - even though it was to protect her boyfriend, Kouji, Manatsu (Manatsu) regretted and was conflicted... However... To Arakawa's relentless demands... Eventually, Manazu can't resist the pleasure... What was the decision made by Manatsu, who was forced to make a choice at the end?