Aya Kōda (幸こう田だ 文あや,, Kōda Aya?) is a civilian who assisted Doppo Kunikida and the armed detective agency. Aya is a young girl with red hair that is worn in a bob with hairpins on both sides of her hair. She wears a tan duffle coat with two off-center fastenings. Aya is a spirited girl who calls herself a warrior of justice and practices martial arts every day. She is stubborn, refusing to take no for an answer, and makes fun of Doppo Kunikida often. She seems to value helping others.