The Day Kokoro is Gone.Aruto relaxing in the hot tub before Kokoro joins her makes for a very awkward scene for the co-dependent and overprotective Iina to encounter, especially since Kokoro is planning to attend a librarian training course in another town the next day. While seeing off Kokoro, Iina cannot help but to impart some motherly counsel to her beloved baby sister as the train is preparing to depart; unfortunately for Aruto, Iina doing a poor job of coping with Kokoro's absence means that she is effectively running the whole library by herself even when Iina decides to instead follow her around while prosecuting divergent speculation as to why they have not heard from Kokoro...