Free: Natsu E No Tunnel Sayonara No Deguchi

"Natsu e no Tunnel, Sayonara no Deguchi" is a Japanese manga series written and illustrated by Tomo Fujimura. The story takes place in a coastal town and revolves around three childhood friends: Kai, Akane, and Akira. As they navigate their relationships and adolescence, they stumble upon a mysterious tunnel that leads to a seemingly idyllic summer.