Six months have elapsed since Yoshiki Tsujinaka"s closest friend, Hikaru Indou, disappeared into the mountains and reemerged a week later with no memory of what happened. Confident that the returnee is not the Hikaru he knows, Yoshiki finally confronts him. Suddenly, "Hikaru" unveils his true monstrous form and begs Yoshiki to keep it hidden, fearing that he would otherwise be killed.
Despite being a supernatural entity, "Hikaru" behaves almost childlike, full of wonder and eager to feel the summer heat, wander through the countryside, and experience everything a human body can offer for the first time. For Yoshiki it matters little whether "Hikaru" is an impostor relying on stolen memories—as long as he never leaves again. Gripped by sorrow, Yoshiki clings to "Hikaru," and it becomes increasingly clear that a dangerous otherworldly force may have descended from the mountains into their village.
