In the case that Garry's blue rose has been stolen by Mary, if Ib picks up a certain item in a certain place, enters the secret room, and returns to the real world after doing a certain thing, this ending occurs.
Having returned to the real world and lost all her memories of the other art museum, including Garry, Ib wanders the art museum by herself.
When she does, it turns out that in a certain place, there is a different painting on display from before she entered the other art museum.
The title of the painting is the same as the title of this ending: "The Forgotten Portrait".
The graphic used for the painting is something the player should remember seeing before...
※From ver 1.04 onwards, one can continue to a New Game Plus from this ending.