The protagonist, Gugayama Yorihime, is a girl who has just turned fifteen. She has received a divine oracle declaring that she will become "Ootsuno-sama." It sounds like a cause for celebration, yet the atmosphere in the Gugayama household as they celebrate her birthday is somehow a bit strained.

In order to carry out the ceremony for Ootsuno-sama, Yorihime is to head to Ubuzumi Shrine. It seems she will be living apart from her family for a while. On the bus bound for the shrine, other girls with horns like hers are riding along as well. Their role is to serve as attendants to Yorihime, who will become Ootsuno-sama. Although it was a lonely departure at first, life at the shrine looks like it will be lively.