Manga Haru Matsu Bokura

From Summer Rain:
Mizuki cannot readily open her heart to anyone, but she is going to turn over a new leaf in high school and change that. But how can she get along with a good-looking group of four, especially with rumors at school about how they met? Although cautious at first, she gradually gets to know their true personalities. A story about good-looking men and the insanity of youth!