Mashiro is a quiet, shy and reserved girl. Though she aspired for Tsukinomori Girls' Academy and managed to get in, she was overwhelmed by the talented individuals around her. As a result, she felt depressed daily until she stumbled upon Poppin'Party's performance in CiRCLE.

She's full of imagination and tends to get lost in her fantasies. Mashiro tends to think negatively quite often, and is afraid of interacting with strangers because she thinks she might give them a bad first impression of herself, as well as make them think she's strange.

She also likes Michelle and all kinds of other fluffy characters.