To conquer the dungeons that suddenly appeared on Earth a hundred years ago, students now attend academies to train as adventurers. Among them are two rivals: Kuroto Sainokami, the academy's strongest delinquent, and Yukihime Mononobe, an elite noble honor student. One day, the two of them find themselves trapped in a dungeon, inside a room that they can't escape unless they're holding hands!? Will these sworn rivals be able to clear this high-difficulty mission and conquer the dungeon...!? (Source: Kadokawa, translated)

The viscount's daughter, Chloe, was the chief magical tools artisan for a country that perished a thousand years ago in her previous life. On the country's orders, she had created many weapons of slaughter. She laments her previous life and decides to, "live a respectable life this time." One day, at her graduation party, her best friend's engagement is broken off because of a lie. Chloe tries to save her best friend by unraveling the truth.