Nayu Hayama (葉山 奈由, Hayama Nayu)
Voiced by: Minori Chihara[3] (Japanese); Brittany Lauda (English)
The protagonist of the story, who also acts as an 'underwear monitor'. She takes keen interest in underwear research. As a result, she is pretty shameless when it comes to her underwear, or anyone else's for that matter. Determined to inform people about the necessities of underwear, she forms the Underwear Appreciation Society with the encouragement of Hiroki.