Suosuomei (voiced by Kana Asumi) is a typical homegirl. She stays at home every day and refuses to go out. She is too lazy to dress, too lazy to take a bath, and even has to rely on her useless brother Tsukuyomi (voiced by Yoshitada Otsuka) to help her eat. Shenchen is not only not angry about his sister's bossy orders, but even enjoys it very much, because in essence, he is a super sister control with a "slaved" physique. Recently, something made Suosuomei very uneasy. Through the "brother monitor" she invented herself, she found that there were three beautiful girls with suspicious behavior around Shenchen - Xieshenjian (voiced by Chiwa Saito), who looks like a loli but is actually a queen, Xieshenjing (voiced by Kana Hanazawa), who looks very ordinary in appearance and personality, but is drowsy anytime and anywhere, and Xieshenyu (voiced by Aoi Nozaka), who looks super mature but is actually only 9 years old. Why does their appearance make Suosuomei feel uneasy? What kind of secrets are hidden in the brother that Suosuomei has been monitoring? Everything is still in the fog.