Suiei-bu Manager Yarichin OB ni Kuwareru.

Miyako Sayama, a busty high school girl, enrolled in a school with a mandatory club activity rule. She intended to join the swimming club, which she had been a part of in middle school, only to discover that the girls' team had been disbanded. As a result, she joined the boys' swimming club as their manager. Her looks and figure immediately excited the male members. However, Miyako soon found herself targeted by the predatory advances of a promiscuous alumnus.. (Source: DLsite, translated)