北海道·函馆市的普通中学生日野光一天早晨突然发现自己长出了一条尾巴,面对亲人和喜欢的人,小光躲躲藏藏地生活着,孰料却被好事的记者盯上了,于是事情向着意想不到的态势发展着......

One morning Hikaru Hino, a high school student living in Hakodate, wakes up to find she has grown a tail. She quickly cancels her first date with classmate Hayato, complicating their relationship. Hikaru's sister makes a fake tail to cheer her up and takes her out around town together, but a reporter captures their photo which leads to a huge commotion in Hakodate. As the tale commotion reaches a fever pitch, another person with a tail, Mr. Yoshida, shows up. As a result, the commotion grows into a full-blown incident that involves the whole of Hakodate.