During the day, Memi Haqaoka (voiced by Satoshi Sakurai) is an ordinary girl studying in the second grade of Saint Bolia Academy. But at night, she will transform into the chivalrous Mysterious Thief Saint Tail.With the help of Liang (voiced by Kikuko Inoue), he started robbing the rich and helping the poor.Meme's biggest rival is none other than her classmate, Asuka Ni (voiced by Okano Kosuke), who calls himself a famous detective.Asuka's strong sense of justice made him determined to reveal the true face of the Holy Girl. His father's career as a detective also facilitated Asuka's arrest. Although he experienced repeated failures, Asuka was not discouraged.In fact, Asuka has always occupied Yami's heart as an ordinary girl, but due to her identity she was unable to express it to him, and wandering between dual identities also allowed Yami to experience some special and thrilling moments.One keeps chasing, the other keeps escaping. What will happen to these two kind-hearted people in the end?