As someone who believes they're 'plain' among the other students, Tsumugi is a girl who is aware that some people might not pick her out as the Ultimate Cosplayer by looks only. She tends to ignore others and stay lost in thought, even though those that try talking to her attempt multiple times. The majority of the time she speaks in a docile way, though becomes extremely passionate when talking about cosplay and anime series she loves. She admits that she has a habit of slipping in anime references and quotes into her speech, which is normally not controlled.

Tsumugi's voice can either be mid toned or higher pitched, but keep in mind that the higher pitched voice should sound as if it's smoothed out.