Gitai Saimin

Murakoshi Shinta is really a student vulnerable to wild delusions. She has kept this hidden all of this while, living his gloomy and mundane life. Some day, a tentacled alien parasite gets control of his penis. Murakoshi complains into it that he is can not walk around outside, with his groin exposed, however the alien assures him that no-one will notice because it has the ability to cloud people's minds.

Thus, Murakoshi utilises that capacity to satisfy his desires.