Unlike her sister Yoshihiro (voiced by Eriko Matsui), who is the president of the student union and is widely watched at school, both appearance and character can only be described as "ordinary". However, on her 16th birthday, the two uninvited guests in the family completely changed Xiao Hong's quiet life. Reticent, weak sense of existence of Sanfeng Bai Night (voiced by Yukiano) and his arrogant and overexuberant sister Sanfeng Meibai (voiced by Yoshida Yoshida) became the residents of Xiaohong's family, while Bai Night's other identity turned out to be Xiaohong's fiance. Not only that, Bai Night also became a transfer student in Xiao Hong's class, even at school! Suddenly there are two more people in the family, everything becomes complicated and troublesome, in the face of this sudden situation, how will Xiao Hong deal with it?