Sayo Kotobuki  

, 寿 沙夜

Ran has a 14-year-old sister named Sayo, who is extremely passionate about the Odaiba Cop show and frequently mimics its main character Detective Kudou. In the first season of the series, Sayo teams up with Masato Iwai to become part of the Junior Detectives. Her signature phrase "datchu" (You bet) was picked up from watching the show as well.