After the Demon King is defeated, a hidden dungeon suddenly appears in a remote border town, said to be filled with unimaginable monsters and incredible treasures. A newlywed woman named Yui attempts to conquer this secret dungeon, but she holds a secret of her own. Once a formidable level 99 martial artist who helped save the world, Yui has since traded her adventuring life for the role of a level 1 housewife. Now, she finds herself drawn back into brutal dungeon conquest, all while keeping her powerful past hidden from those around her.

The central conflict arises from the dual life Yui must lead. Having fallen in love and chosen to become a devoted homemaker, her husband remains unaware of her legendary history as a warrior. When he decides to face the dangerous dungeon himself, intending to protect his seemingly ordinary wife, Yui accompanies him. She must carefully navigate each expedition, hiding her overwhelming strength to maintain her new identity while ensuring their survival against threats only she can truly handle. The story follows her secret journal of dungeon conquest, balancing the mundane tasks of a newlywed with the extreme violence of exploring a treacherous labyrinth.

The narrative unfolds through several key phases. The premise establishes Yuis secret past and her motivation for retiring to a peaceful life. The exploration of the hidden dungeon serves as the primary setting for action and conflict, where the gap between her level 99 combat abilities and her level 1 housewife status is constantly tested. Early narrative arcs focus on Yui protecting her unsuspecting husband from afar, while subsequent developments likely explore the complications of maintaining her secret as the dungeons challenges escalate.