Black Door also known as Gate of Blackness. It can only be opened from the outside. The black door holds an insane person inside, named Shin Alford. Shin went mad after his real father and his soon to be wife died. This door has no warning on it but the Alfords know not to go inside a black door and tell everyone who enters the home.
The door appears as a black door with a red light shinning through every single crack. Ikki saw this door and was creeped out, asking what was on the other side and going to open it when Elica didn't answer. the twin sister of Elica, Alice stopped him and asked him if he truely wanted to know, which she opened it and her brother Shin who was held inside tried killing her but didn't work since Jack knocked him unconscious.