During the fall season, Tsuruta, a high school student, sets out on a reluctant mission to find Luna, his sister's lost cat. He soon stumbles upon the feline near a tunnel and begins to chase it through the passage. Emerging on the other side, Tsuruta is baffled to find his previously deceased friend Kamei standing before him, with a nihilistic outlook on life. Unsure of what's real, Tsuruta enlists Kamei's help in finding Luna. As they search for the cat together, Tsuruta's buried regret surfaces as his past and present start to merge.
