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 and plead with Yoshiki to keep his secret, insisting he doesn’t want to kill him. Despite his terrifying true form, "Hikaru" behaves with an almost naive curiosity, marveling at summer warmth, rural life, and the simple joys of having a human body. To Yoshiki, it doesn’t matter if "Hikaru" is an impostor living off borrowed memories-he just can’t bear to lose him again. But as Yoshiki clings to "Hikaru" in his desperation, it’s clear something sinister and otherworldly has crept down from the mountains into their village.