Kohaku theorizes that Hitomi unconsciously used magic on herself that resulted in her monochromatic world, and has Aoi do all sorts of embarrassing experiments with Hitomi to try and get a hint on how she can break the spell, such as calling him by his first name and having them come close to each other. These experiments prove to be a huge failure though and Kohaku resolves to practise time magic to bring Hitomi back to her original time. However, the club members feel a sense of sadness remembering Hitomi's imminent departure. Hitomi herself, is unwilling to go back. (Source: Wikipedia)