Game encompasses the lives of Kurusu Itsuki as the first protagonist, and his best friend, Kidou Naoya as the second protagonist. Itsuki is a bit of a loner, and a bit on the emo side at that (kind of gloomy, not well-spoken and with a bit of an inferiority complex); he's basically Shinji Ikari moved from Evangelion into a random ero game, with a new haircut and glasses. Despite this, he is best friends with Naoya, who happens to be one of the most popular guys in school (as in, girls contantly ask him out and proposition him for things, even older girls). Itsuki's life takes a rather interesting turn when one Ichinose Kyo approaches him. Kyo in this story is a girl with a bad reputation, though she doesn't seem to mind the negative attention. Either way, she asks Itsuki to help her cheat at some exams that are coming up. In return, Kyo offers her virginity. As simple (and pointless) as this may sound, this set up leads to an emotional rollercoaster for Itsuki, not to mention the two girls he can end up with and the third girl that can potentially ruin his life. Aside from Kyo, both Sonomura Madoka (Kyo's childhood friend) and Kirisawa Iori (Naoya's would-be girlfriend) have a ton of emotional baggage that the player will get to witness, regarless of who Itsuki goes after.

[From Moroboshi Yuumei blog]