Nono Sasaki is an ordinary girl whose greatest passion is playing video games. After a tragic accident, she finds herself summoned directly into the world of her favorite game, but not as the hero she might have expected. She is reborn as the Demon Lord, the very antagonist the game's story is built around. Her new existence comes with a terrifying condition if she stops acting as the Demon Lord, she will die.

The central conflict arises immediately upon her arrival. The princess of the enemy kingdom she is meant to destroy looks exactly like Nono's favorite character from the game, a figure she deeply adores. This lookalike princess is the very person the Demon Lord is fated to defeat, creating an impossible dilemma. Nono has no desire to harm her beloved character, yet her survival depends on successfully playing the role of the Demon Lord. Her solution is to try and fail at being a proper villain, leading to a series of comedic attempts to get closer to the princess rather than vanquish her.

The story takes place within this fantasy game world, with the dynamic between the reluctant Demon Lord's castle and the princess's kingdom serving as the primary setting. Nono Sasaki is an otaku whose deep affection for a fictional character drives the entire plot. Her living situation forces her to navigate the expectations of her new demonic subordinates while hiding her true feelings. The princess of the hostile nation serves as her emotional anchor and the object of her obsession, completely unaware that the terrifying Demon Lord actually wants to befriend her or, at the very least, not fight her.

The first major narrative arc establishes Nono's summoning and her desperate struggle to understand the rules of her new life. She learns the specifics of her curse and first encounters the princess, which solidifies her refusal to follow the game's intended storyline. She tries to act like a proper Demon Lord in name only while secretly seeking any opportunity to interact with her foe. The second and final arc follows Nono as she grows more accustomed to her position. She has learned the basics of managing her domain, but the core problem remains unsolved. She cannot bring herself to confess her feelings or reveal her identity to the princess, who also serves as a potential key to her freedom. The story concludes as her precarious balancing act between her duties as the Demon Lord and her personal desires reaches its endpoint.