The story of Ib is about a young girl named Ib who had arrived at the Guertena Art Gallery with her parents. While her parents were at the reception desk, Ib asks to wander off on her own around the art gallery. When Ib observes a certain painting called Fabricated World (known initially as ??? World to Ib), the lights start to flicker.

Ib will soon find out that everyone had disappeared and that she is all alone.

According to the game's Japanese dialogue, the game takes place at some point after the year 6235.