Angelus Errare are areas in Momodora II, that serve a function of corridors, connecting bigger areas together.
Usually one or two rooms in length. Most of the time the rooms are just attaching two loading points. However, two of them are more interesting.
The one connecting KoHo Plains with KoHo Plains is interesting because in it you meet Nanashi Reinol. It also includes a locked door that unlocks once the player starts a New Game +. That door leads to the developer room.
The other notable one connects Rahart Hall with Ivory Netherworld. That one has a force field block the path until all of the Statues have been prayed under. That one also has Mai mentioning the force field in it.