Reiko is a member of Occult Research Club. She is well-known for her knowledge and obsession with the supernatural, leaving her at odds with Sket Dan member "Switch".
Reiko's obsession and fascination with the supernatural began in middles school. She was a friendless girl, with no friends and her usual frightening [and very ghostlike] appearance. One day, she found that she had a crush on a boy, who immediately rejected her on the basis that she was "too creepy". Ever since that day, her obsession with all things frightening and supernatural has only grown.
Reiko was created by the mangaka Kenta Shinohara for use in the manga Sket Dance. She was first introduced in the third chapter of the manga, "Ghost in the Incinerator", and the fifth episode of the anime with the same name. In the Drama CDs, Reiko was played by Yu Kobayashi. However, for the anime, her voice actress was changed to Fumiko Orikasa.
In the first Sket Dance popularity poll, Reiko came in 15th place, tying with Student Council member Mimori Unyu. In the second popularity poll, Reiko dropped several places to 32nd place, tied with Saint Cain-kun.