Atsuko Chuuzenji

As the younger sister of Akihiko Chuuzenji, she currently resides at her brother's home. Blessed with a quick mind and a proactive nature, she stands out as one of the rare few who can openly voice her frustrations toward the eccentric Akihiko. Throughout the story, she plays a vital supporting role, forging connections with the heroine Kanna Kusakabe and others, and actively contributing to investigations into various school mysteries through her bright personality and keen curiosity.