Hoshino Star, a male high school student who lives leisurely in the countryside, has a unique power—that is, being able to get along with any animal! Although Hoshi spends his days feeling supreme joy in interacting with animals, on the other hand, he also has a great dislike of humans. Kirari Yozora, a childhood friend who struggles with her extreme personality, suddenly thinks one day. What would Hoshi think if there were animals like humans? At that time, a mysterious object comes flying with a roaring sound. Appearing from the other side of the dust cloud is the most terrifying and worst visitor with cute fur ears and a tail.

Mikado Shuuji is just an ordinary guy, but he has a very unusual knife that he uses for cooking. It's actually a famous short sword that marks its owner as the head of the ninjas, and now there are hot ninja girls coming after him to take it back. Hinamori Botan is one of those hot ninja girls, but her efforts to attack Shuuji mostly end up inadvertently stripping her. After she concludes that she does not want to steal the sword and kill Shuuji, she ends up deciding to serve him as a ninja instead. Now she must protect him from the other ninja that come to claim his sword and his life!

After an accident, our protagonist Amagi Kouichi becomes involved with Itanami-san, a well known beauty of his school and secretly a vampire.