Miyako Toudaiji, is a high school girl who lives with mom and dad. Her dad is detective. Miyako's best friend is Kusakabe Maron. Miyako and Maron, the most unlikely friends. These two have known each other for many years. Infact their mothers were best of friends. Miyako was befriended by Maron in Kindergarten. Hardly any one likes Miyako because she was very blunt on how she would handle things, and the other children in class thought that Miyako was being mean. Maron defended Miyako's actions and even explained why Miyako did the things she did. From that moment on those two had been close friends. Maron has always tried to protect Miyako from others. That is why Miyako determined to prove Maron is not Kaitou Jeanne to the class.
Miyako also has a soft spot for Chiaki, however she does put her feelings aside when she realizes that Maron also likes him. Miyako will make a spetical out of her self to get Chiaki's attention but, when it comes to Maron Miyako all but sets up Chiaki and Maron to get together.