The Morose Mononokean S01 E02 The Ant

When Ashiya begins working part time at the Mononokean, the master Abeno impresses upon him that he should pretend not to see any yokai other than the Mononokean's clients. However, the kind-hearted Ashiya is unable to keep his word, and the yokai won't leave him alone. Based on their surprising strength and numbers, Abeno believes there must be a powerful demon serving as their leader.