Birdmen manga

Birdmen summary:

Eishi Karasuma (15 years) is a loner with a monotone life. His only friend is Mikisada Komoda (14 year). They venture together while skipping course. One day in a park, they met Tsubame, a very energetic girl and Rei Sagisawa (15 year), a boy that attend the same middle school. On their way back, Eishi and Mikisada take a bus which lose its track and fell from a cliff. Eishi tries to go out when he suddenly spots a young boy with wings...