Saki Osanai dies after mistaking a cat-shaped plastic bag for a real kitten and throwing herself into traffic to save it. In the afterlife, she bargains with the gods for a second chance and makes one wish: a tall, voluptuous body that would make any man fall for her at a glance. The gods grant the wish, but her request is misinterpreted. She is reborn in a fantasy world as Satie, still stuck in a petite, childlike form. Instead of a beauty-enhancing figure, she receives a cheat ability that multiplies her growth rate by one hundred, allowing her stats to increase a hundred times faster than a normal person. Worse, the god of the underworld informs her that she is cursed with eternal youth: she will never age past the appearance of a young girl as long as she continues to repeat the passive, self-defeating patterns of her previous life.

Determined to break the curse, Satie embarks on a journey of self-improvement and world conquest. She adopts a hellhound she names Kuro, spoils it rotten, and uses her overwhelming power to carve a path through the continent. Her driving goal is to find true love and grow into the adult body she dreamed of, but her explosive strength, blunt personality, and relentless ambition attract far more attention than she wanted. Every empire, monster, and scheming noble she encounters becomes another obstacle she must crush, all while she remains trapped in the form of a small girl. The narrative follows her chaotic adventures as she tries to live peacefully, only to find that her own desires and the reactions of everyone around her keep dragging her into larger conflicts. Major arcs include her conquest of hostile territories, her deepening bond with the hellhound Kuro, and her ongoing struggle to understand what it truly means to grow up, both physically and emotionally, in a world that refuses to let her stay small.