"Hikaru" it's not actually the human boy Yoshiki who grew up with. The real Hikaru died on top of a mountain, however, Yoshiki figured it out and "Hikaru" had to explain what happened. He's now supernatural entity, a mimic from the "Other Side" often linked to the local mountain folklore took over Hikarus body, copied his memories and now pretends to be him. Only Yoshiki knows what actually happened to his Hikaru. The "Hikaru" has a stomach and chest cavity to serve as a definition proof that he is no longer human. When he slits open his own torso, when someone sticks their hand directly in his stomach cavity. They wont feel human organs instead it feels like raw marinated chicken. However, "Hikaru" has his own feelings, separated from Hikaru's actual emotions. He's still playful and goofy and everything he always is— but he has his own personality in a way