He's is the real one. It goes like this: Chiwoo sacrifice his life for Hwan, so he can't suffer anymore. Thing is, due to his sacrifice, he lost the battle between dark and light. The wish of Hwan, was to stay always with Chiwoo, but as he died, they can no longer stay together. After his death, Hwan's life has no meaning, so Moony tries to fulfill his wish. As Chiwoo is dead, Mooney uses some extra magic, and gives Chiwoo his life back, but he reverses time till the accident of Chiwoo Family, making it never happened (this way, Chiwoo will have a happy life) It's like all the things that happen in the story,never existed, cause everything was erased, due to the change in history. This way, Chiwoo is happy and Hwan can have his second chance. Hope this clear this for you!
I was soo CLOSE to drop this manga cause of so many plottwists AND I DONT GET THE ENDINGGGGGG IS CHIWOO RLLY DEADD OR WHAATY (would’ve been better if the chiwoo in the end is really the real one cause i feel bad for him ykyk)