The day before he begins attending high school, Ashiya Hanae becomes possessed by a strange fuzzy yokai. Being possessed causes him to fall ill, and while spending the start of his high school life repeatedly making trips to the nurse's office, he comes across the contact information of the Mononokean, which specializes in exorcising yokai, and decides to call them. When Ashiya finally visits the Mononokean, he meets the morose master Abeno Haruitsuki.
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.
After making friends with his classmates Saga and Fushimi, Ashiya believes the high school life he dreamed of may finally be his. But before he has the chance to enjoy his new life, he's instructed to go to a certain temple alone to find and return a yokai's lost possession. At the temple, Ashiya meets a girl named Fujiwara Zenko, and it seems the lost possession in question has something to do with Zenko's father, the head priest...
When Ashiya hears that Abeno will be going to a pharmacist called the “Kiyakudo” in the Underworld, he asks to go with him. Though Abeno is reluctant to bring a human to the Underworld, he relents when the Mononokean suggests that Ashiya accompany him. Concerned for Ashiya, Abeno forbids him to travel in the Underworld alone, but Ashiya finds himself unable to keep his word again...
The Legislator, one of three influential figures of the Underworld, issues a rule that Abeno must bring Ashiya to see him. Unable to defy the Legislator's rules, Abeno is forced to pay a visit to him with Ashiya in tow. As Abeno hired Ashiya without informing the Legislator, he now seeks to determine for himself if Ashiya is truly worthy of being an employee of the Mononokean. What will the Legislator conclude?
Abeno is hired by a certain yokai to find a human woman's missing ring and return it to her. Unable to find the ring on his own, he gets Ashiya to help him look for it. During their search, Ashiya demonstrates a surprising talent. The ring is found, but when the time comes to return the ring to the woman, Ashiya and Abeno disagree over how they should return the lost ring to the woman.
Yuki Kaji
Hanae Ashiya
Tomoaki Maeno
Haruitsuki Abeno
Ayahi Takagaki
Zenko Fujiwara
Ikue Ōtani
Yahiko
Yoko Hikasa
Koura