"Oversummoned, Overpowered, and Over It!" centers on Akira Oono, a young man who is repeatedly summoned to a fantasy world as a hero to defeat the Demon King. However, unlike typical isekai protagonists, Akira grows increasingly frustrated with the repetitive nature of his summonings. Each time he is summoned, he defeats the Demon King, only to be sent back to his original world, only to be summoned again shortly after. This cycle leaves him exhausted and disillusioned, as he is denied any lasting peace or reward for his efforts.

The story explores Akira's growing resentment toward the summoners and the world that exploits his power without regard for his well-being. Despite his overwhelming strength, Akira is not invincible emotionally, and the constant battles take a toll on his mental state. The summoners, oblivious to his struggles, continue to treat him as a disposable tool, further fueling his frustration. Akira's interactions with other summoned heroes and the inhabitants of the fantasy world highlight the disparity between their idealized expectations and his grim reality.

Key characters include the summoners, who represent the various factions vying for Akira's power, and the Demon King, whose repeated resurrections perpetuate the cycle of conflict. Akira's relationships with these characters are strained, as he struggles to reconcile his role as a hero with his desire for autonomy. The narrative delves into themes of exploitation, the cost of power, and the dehumanization of individuals treated as mere instruments for others' goals.

As the story progresses, Akira begins to question the morality of the summoners and the system that perpetuates the endless cycle of summoning and battle. His journey becomes one of self-discovery and resistance, as he seeks to break free from the constraints imposed upon him and find a way to reclaim his agency. The manga balances action and introspection, offering a nuanced portrayal of a protagonist who is both overpowered and profoundly vulnerable.