Is It Wrong to Try to Pick Up Girls in a Dungeon? Familia Chronicle, Vol. 1: Episode Lyu (light novel) — Fujino Omori

Sometimes carrying out justice requires...cross-dressing?!

When a troubled couple tells the story of how their daughter was taken to pay off a gambling debt, Lyu's conscience and the legacy of Astrea Familia compel her to take action!

The many skills Lyu learned as an adventurer are formidable, but she'll need more than brute force to challenge the influential Grand Casino. Unable to sneak or fight her way inside, Lyu puts all her trust in Syr's rescue plan: Go through the front door posing as Count Maximilian and his beautiful wife!