Watch Natsu e no Tunnel, Sayonara no Deguchi Online

Kaoru Tono heard a rumor: The laws of space and time mean nothing to the Urashima Tunnel. If you find it, walk through and you'll find your heart's desire on the other side...in exchange for years of your own life. One night, Kaoru just so happens to find himself standing in front of a tunnel that looks suspiciously like the one the rumor describes. He finds himself thinking of Karen, the sister he lost in an accident five years ago. To Kaoru's surprise, he's been followed by the new transfer student Anzu Hanaki, who promises to help him experiment with the mysterious tunnel—but what does she want from Kaoru in exchange? And what will he have left to give, after the tunnel's done with him?

Marion is a young schoolboy who prides himself on his adherence to a philosophy he calls "rationalism". Because of his disdain for emotional display, he ignores anything remotely akin to affection. But when he's entangled in a romantic affair with an older courtesan, his rationalism is revealed to be little more than a cover for his own emotional immaturity. Learning to love, Marion blossoms under his older lover's care but unfortunately, Marion has yet to learn the true price of the affair.