Episode 17: Shinobu Time - Part 4

In exchange for her help, Gaen requests three tasks from Koyomi, all being connected to Suruga Kanbaru, formerly known as Suruga Gaen. Izuko reveals herself as her aunt, but she doesn't want to be introduced to her as one, because she cares for Suruga's feelings. When Koyomi accepts, she shows the darkness' true motive - it is after apparitions not behaving like they should, and this time it isn't after Shinobu, but Mayoi. She exposes Mayoi as a "ghost of a ghost", who should have passed on on Mother's Day, when she finally found her way home; she also stopped leading people astray, neglecting her duty as a lost cow. After Gaen leaves, Mayoi realizes she has to pass on, rather than be eaten by the darkness, and thus she bids Koyomi farewell by kissing him and telling that she loved him. Four months later, Koyomi tells the story of the incident to only one person - Ougi Oshino. On his way home, he realizes he never told Mayoi one thing he should have said - goodbye.