The Tunnel to Summer, the Exit of Goodbyes: Ultramarine

夏へのトンネル、さよならの出口 群青

Kaoru Touno hears a rumor about the Urashima Tunnel: whoever enters is granted their heart's deepest wish, in exchange for years of their own life. He finds a tunnel matching the description on the very night he's thinking of his younger sister Karen, who died five years earlier. New transfer student Anzu Hanashiro follows him in and offers to help him investigate the tunnel, though what she wants from Kaoru in return is unclear. This manga adapts the light novel of the same story under its own title, Ultramarine.