Aitsu ni Koishita Yottsu no Wake

From Manga Rebels:

These stories about 4 typical high school girls' love life are Yokoyama Mayumi first work.

1. A Real World
   After 2 years Eri got back together with her ex-boyfriend.

2. Lip Lock
   Nina made him break his "right hand" so she substituted XX (sexual favours?) to take care of him.

3. That Is My Weak Point
   Risa's ex-boyfriend stole embarrassing photos of her, and now she wants to get them back.

4. Hotel Red Peacock
   With the current course of events, Chika needs to make her bad tasting Love Hotel prosper.