SPOILERS
basically, this kid named Hikaru goes into the mountains but ends up slipping, dying, and going missing. Huge scary monster-thingy finds him and slides into his body. Apparently, Yoshiki (other main dude) had searched for Hikaru when he went missing and found him dead. It turns out though that he wasn’t dead (via big scary monster inhabiting his corpse) and “Hikaru” continues life as normal. HOWEVER, Yoshiki saw this dude dead and was like “wtf” and so he confronts “Hikaru” and his suspicions that Hikaru isn’t really Hikaru are confirmed. Anyways, Yoshiki’s like “it’s freaky, but I’m a freak” and so, knowing Hikaru is not Hikaru, decides to act like he is Hikaru.
It’s more psychological mindfuckery than horror, but it does have a lil bit of murder, body horror, and terror. Yoshiki kinda just gaslights himself into thinking everything’s okay because he has issues, is harboring a crush, and is fucking terrified of dying.
Hey guys so give me a quick summary of this, I'm fine with spoilers