The Tunnel to Summer, the Exit of Goodbyes

Tono Kaoru heard a rumor: the laws of space and time mean nothing to the Urashima Tunnel. If you find it, pass through it and you will find the desire of your heart on the other side… at the cost of years of your own life. On the night Kaoru finds himself facing a tunnel that strangely resembles the one in the rumor, he thinks of Karen, the sister he lost in an accident five years ago. To Kaoru's surprise, the new transfer student Anzu Hanaki follows him, promising to help him experiment with the mysterious tunnel, but what does she want from Kaoru in return? And what will he have left to give once the tunnel has taken everything from him?