Lol. This isn't that good of an anime. It's got a pretty poor story and it's so dramatic and unreal it's almost hard to watch at times. Characters are weird and spazzy, manipulative, needy, and just not written well. Spoilers entailed.
The female characters, including the heroine, are all very obsessive and crazy. Honestly, for a high school girl, Sai is pretty much the Hitler of this genre and goes as far as to get Momo almost raped just so she can be "the best girl" and despite this, they actually come out on friendly terms in the end despite Sai blackmailing Momo's boyfriend, getting her "boyfriend" to rape Momo, managing to turn the entire school on her, etc. It's just so wild it's entertaining.
Honestly, if you want to sit down and watch something extremely stupid, dramatic and all-over-the place, Peach Girl is the anime to watch. It's pretty much a soap opera. But instead of the mafia or something, you get insane high school girls. It's more funny for this than anything.