: Another emotional insert track included in the official soundtrack. Original Soundtrack (OST) The background score was composed by Harumi Fuuki and includes several key atmospheric pieces:
: Time inside the tunnel moves much slower than outside; seconds inside can translate to hours or even days in the real world.
The story is set in a quiet rural town rumored to contain the "Urashima Tunnel," a local urban legend. The tunnel operates on the folklore principle of Urashima Taro: time passes differently inside than outside. However, the specifics are inverted. Inside the tunnel, time nearly stands still, but for every few seconds spent within, years pass in the outside world.
Written by Mei Hachimoku, the original light novel provides internal monologues and deeper lore about the Urashima Tunnel that the movie omitted due to time constraints. 2. The Manga Adaptation
