Summer of the third year of high school. In the class where the protagonist, Guest, has transferred, there were three overwhelmingly beautiful girls known by everyone in the school. A dream-like situation that everyone would envy—however, their true natures were "Unconquerable Monsters (Heroines)" who had crushed the hearts of every man involved with them beyond recovery.

A cold queen who erases your very existence the moment you speak of affection. A psychopathic young lady who views humans as glitches and negates them while smiling. A soft and fluffy girl who will date anyone, but drives men to despair with the bottomless void in her heart.

Sweet feelings and cliché romance techniques don't work at all. One wrong move, and you're socially dead. In the middle of a classroom that feels like a minefield, Guest's incredibly dangerous school life begins—!