18+ Soreyuke Marin-chan

Dr. Narutaki, a genius who is trying to preserve true Japanese men, not the losers they are today, needs semen from hundred specimens. The problem is that these hundred specimens wouldn't give it to him voluntarily, so he comes up with a plan. He gets Marine, a girl from an all girl school, and put in her a ring and a special costume that changes to a man's desire and won't come off until she gets all hundred semen specimens. Now to get in her way, South Pole One, an android created by the doctor's jealous assistant Marilyn, is interfering by exhausting and taking the men's semen first, making it a race against time.

(Source: Wikipedia)