Aire, a working-class girl gifted with an extraordinary aesthetic eye, scrapes by earning daily wages as a mail carrier. While attending an auction held at a noble estate in search of a certain item, Aire uncovers that forgeries have been mixed in among the lots. That revelation draws the attention of the auction’s organizers, led by the young marquis and head of his house, Baltroot—and soon, Aire finds herself caught up with them…!?