The Summer Hikaru Died - S01

Six months ago, Yoshiki Tsujinaka's best friend, Hikaru Indou, vanished in the mountains and reappeared a week later with no memory of what happened. Convinced the person who returned isn't the real Hikaru, Yoshiki finally confronts him-only for "Hikaru" to transform into a monster, pleading with Yoshiki to keep his secret so he won’t have to kill him. Despite his terrifying true form, "Hikaru" acts strangely innocent, marveling at the summer warmth, the countryside, and the simple joys of living in a human body. Yoshiki doesn’t care if "Hikaru" is an impostor using stolen memories-he just can’t bear to lose him again. But as Yoshiki clings to "Hikaru" in his grief, it’s clear something dark and unnatural has crept down from the mountains into their village.