omori is a shield to protect the truth. While Sunny is in omori's form, if the truth comes near, omori will destroy it. Sunny controls omori's body, but whenever the truth tries to come out, Omori takes control and either escapes or destroys that. For example, at the beginning of the game, while Basil tries to tell the truth, Omori teleports to White Space. In black space, while Basil tries to tell the truth, Omori kills him. and eventually, while in red space, omori takes full control (here the player's control is taken away) and stabs Basil. then he sit on the throne red hands. Of course, sunny can no longer be in Omori's body, as Omori has taken full control. so that's why he is in white space with his real life body after he sleeping in basil's house.