"There is a phenomenon called the Urashima Tunnel, which exists outside the boundaries that constrain our reality. Unbound by such restrictions, it can achieve the otherwise impossible, journey wherever a mind can conceive, and bring the one thing that they most desire. But the cost of using the tunnel is staggering: a portion of one's own existence. Yet... when Kaoru Tono discovers something matching the Tunnel's description, he can't help but think...