Love Junkies

Sakibara Eitaro is a 22 year old virgin. He's desperately trying to get laid - and that happens right at the beginning of the story with a girl named Maiko.
After that, Eitaro's relationship with girls change suddenly: he starts feeling more secure of himself and sex and starts meeting lots of girls. Three of these girls have a very important part in his life (Ninomyia Emu, Ide Miho and Jii Shinako) and his love adventures revolve around those women.