Kotori Otonashi works as an office clerk at 765 Production. She is the daughter of a former idol connected to the agency's president, Junichiro Takagi, though her own past as an idol is unconfirmed. Her appearance includes short green hair, brown eyes, and a distinctive mole on her right cheek, frequently concealed by her yellow microphone headset. She typically wears a white dress shirt, a black and green vest, a large purple ribbon bowtie, a black skirt, black stockings, and white high-heel shoes.

Her personality combines open-mindedness and intelligence with moments of shyness. During quiet times at work, she often dozes off or slips into vivid daydreams, revealing her fujoshi interests. She actively browses internet forums like 2chan, which sometimes leads others to view her as a pervert. Despite not performing as an idol, she retains a love for singing [citation:].

Her background involves a familial tie to idol history; a photo shows her mother, a former idol produced by 765 Pro, alongside Takagi and reporter Kuroi. While her age isn't officially stated, contextual clues place her in her twenties, slightly older than her colleague Azusa. Her three sizes are undisclosed.

Within *THE IDOLM@STER MOVIE: Beyond the Brilliant Future!*, Kotori appears among the 765 Production staff, assisting with preparations for an arena concert and the integration of backup dancers.

Her name translates to "small bird," reflecting thematic elements. She shows fondness for the producer, often requesting shared meals or drinks. Her designated character color is *Hiyoko-iro* (light yellow). Her birthday is September 9, with blood type AB, height 159 cm, and weight 49 kg.