Based on the eroge by Marine. Makoto is an ordinary university student who frequently visits a nearby swimming pool to swim and observe women in swimsuits. One day, he is asked to teach Marina how to swim. It seems she cannot swim at all. While he touches her body, he gets an erection. Marina notices it and gives him a blowjob. When he touches her vagina, she cries out in pleasure and achieves female ejaculation. His unknown erotic ability comes into bloom! Make all women—from a university student to a married woman—ejaculate with your fingers!