Cleaning Brush (ハタキ Hataki, lit. Feather Duster?) is Olson the librarian's key item in Knights in the Nightmare. It can be found in Scene 7 on both paths. The method of obtaining it varies by the story version. In Maria's path, it is found by breaking the pot and letting it reappear; in Mellia's story, the barrel in the lower portion of the map has to be opened.