Aitsu ni Koishita 4-ttsu no Wake
アイツに恋した4つの理由〈ワケ〉
These stories about 4 typical high school girls' love life are Yokoyama Mayumi first work.
Story 1: A Real World
After 2 years Eri got back together with her ex-boyfriend.
Story 2: Lip Lock
Nina made him break his "right hand" so she substituted XX (sexual favours?) to take care of him.
Story 3: That Is My Weak Point
Risa's ex-boyfriend stole embarrassing photos of her, and now she wants to get them back.
Story 4: Hotel Red Peacock
With the current course of events, Chika needs to make her bad tasting Love Hotel prosper.
(Source: MangaRebels)