Invisible Hentai Man(2013)

Hideo receives a small bottle containing invisiblity pills as a thank-you for helping a Chinese man who was being harassed on the street. The first thing he does after becoming invisible is spy on his beautiful coworker, Seika. Hideo starts to thoroughly enjoy his life as an invisible man, but at one point another invisible man appears on the scene and tries to win Seika’s affection. Can Hideo win the battle for her heart?