Kagami Kazuya is an ordinary school boy who has one slightly odd habit: he carries around the obi of a kimono that belonged to his late mother. This wouldn't be a big deal, until the obi reveals itself to be a tsukumogami!

Kazuya and class rep Chisato find themselves trapped in the school library, and it's up to Kiriha's knowledge of spirits and the forms they take to get them out.

A towering priestess shows up looking for Kazuya, and the person who sent her has an offer he and Kiriha might not be able to refuse.

Kiriha is being battered by the water goddess Kukuri-hime's attacks, when a mysterious vision gives Kazuya advice on how he and the tsugumomo might manage to survive.

Now that Kazuya has accepted the duty of exorcising any supernatural trouble that crops up, it's up to Kiriha to whip him into shape.

When the entire school starts acting like characters from a dating sim, Kazuya and Kiriha are forced to find the amasogi responsible before the affected people do something they'll regret.