Full original title: ハチナイ外伝 戦力外!カタトちゃん Full English title: please add it here Artist: bkub Source
A series based on the smartphone game Hachigatsu no Cinderella Nine, following the antics of first-year high school student Ikusa Katato. Serialized on the smartphone game's official website from August of 2016 to August of 2020.