From ShoujoMagic:

Ryou has the biggest breasts of any shoujo manga heroine to date! But life isn't any piece of (cheese) cake, because she's constantly being assaulted by perverts who want to cop a feel. The first man who doesn't obsess over her assets turns out to be the first man she ever wants to have obsess over her, though there's something strange about him... One time she's with him, he's a sweet masochist, the next time he's a bold sadist. Which does Ryou like better? The S or the M? She'll have to make a choice, because it turns out that she CAN'T have both. Find out the surprising reason why one face has two personalities!

Includes short stories:

Volume 1:
Gattsuiteke! - It's Unintentional!
Chinatsu has liked her guy friend, Shinnosuke, who she fights with allot, for a long time... Will she be able to be together with him when there's another guy confessing his feelings right in front of him?

Only
A sort of prequel about Masaki and Shingo when they were younger, but mostly focuses on Shingo because he's the more troubled one.

Volume 2:
Prince of Summer
Nozomi-chan's got two of the school's most popular guys, Ken Tamae and Kaname Yuuki, confessing their love to her at the same time... What's a girl supposed to do when her world is suddenly so confusing? Especially when she used to wish that she could get her hands on one of the two...

Volume 3
Shiitake - The Mushroom Girl
Keiko Shita sees herself as a dark person, and so does everyone around her... But what if that could change? What if the popular boy, Teru Hinata, could change that?