Volume three of Kamisama Kiss opens with Nanami being invited to a party by Himemiko. Due to feeling very uncomfortable with the idea of Tomoe helping her put on a kimono, she attends the party in her school uniform. When they arrive at the party a number of carp princesses descend upon Tomoe, which makes Nanami very unhappy, however, she lets him go anyway.
Himemiko meanwhile whisks Nanami off to play dress up. It seems that Himemiko believes that Nanami has a relationship with Tomoe. Nanami denies this, but Himemiko is insistent. Meanwhile, Tomoe is trying to escape from the carp princesses. When Tomoe finally sees Nanami post makeover, he is very impressed. The carp-girls meanwhile are very jealous and try to drag him away. Tomoe however stands firm. He tells Nanami she looks beautiful, which has a considerable effect upon Nanami.
After the part, Nanami rescues a white snake while at school. The snake leaves behind a mark that indicates that Nanami is engaged to the snake. Tomoe is extremely displeased by this turn of events and decides that he must pose as a student in order to stay close to her. Tomoe’s human disguise is superficial at best and results in Nanami taking him aside and explaining the Importance of Cover Stories.
The white snake turns out to be the former shinshi (familiar) of a shrine. He kidnaps Nanami, and has plans to marry her. Nanami needless to say, is not on board with this idea, but the snake, whose name is Mizuki, does not seem interested in being reasonable or even sane. Nanami’s stay is less than pleasant since the snake and the attendant servants know nothing about taking care of humans. (It is also unpleasant because Mizuki is Norman Bates levels of creepy.) Despite the situation, Nanami ends up feeling sorry for the shinshi, because it turns out that the white snake’s former master has “returned to nature,” leaving him alone.
Meanwhile, Tomoe eventually finds the location of Mizuki’s shrine, which is in an abandoned village on the bottom of a lake. A fight ensues between Tomoe and Mizuki that ends when Tomoe threatens to destroy a plum tree sacred to the kami who had formerly occupied the shrine. Tomoe fully intends to destroy Mizuki, but Nanami is a soft touch because she forgives Mizuki for kidnapping her and promises to visit Mizuki in the future.
A little later, there is gender bending hijinks when Nanami becomes sick. Because she cannot afford to miss school, Tomoe disguises himself as Nanami, and goes to class for her. Kurama turns up and makes flirtatious overtures at “Nanami,” which Tomoe does not appreciate, and then Kurama offers a warning about the increase of “miasma” at the school. (The reason why this is significant is because more “miasma” means more yokai.) We get a demonstration of the problem when a yokai turns up and starts harassing students in the girl’s locker room. Working together, Kurama and Tomoe get rid of the yokai.
While the fox-boy and the crow-boy are having adventures, Nanami gets a visit from Mizuki. Under the guise of being friendly, he attempts to undermine Nanami’s relationship with Tomoe. He gives Nanami and dream that reveals some of Tomoe’s past to her. (Actually, he may be intending this as a genuine overture of friendship since Tomoe has a very shady past. His methods however, stink.) Then Tomoe comes home, and kicks Mizuki out of the house.
We end with Nanami being somewhat disturbed by the dream, but passing it off as a nightmare.