"I Kept Pressing the 100-Million-Year Button and Came Out on Top" centers on Allen, a young man who discovers a mysterious button in a hidden room beneath his school. The button promises immense power but at a steep cost: pressing it requires enduring 100 million years of solitary confinement in a timeless void. Despite the unimaginable toll, Allen repeatedly presses the button, accumulating vast amounts of time and emerging with unparalleled strength and knowledge. Each press transforms him further, granting him abilities far beyond human comprehension.

The story explores Allen’s journey as he navigates the consequences of his choices. His newfound power draws attention from powerful entities, including rival factions and supernatural beings, all seeking to exploit or eliminate him. Allen’s interactions with these forces reveal the broader world’s complexities, including ancient conflicts and hidden truths about the button’s origins. Alongside allies like Rin, a skilled fighter with her own mysterious past, Allen confronts escalating threats while grappling with the psychological and emotional scars of his prolonged isolation.

The narrative balances action and introspection, delving into themes of sacrifice, resilience, and the cost of power. Allen’s growth is marked by his struggle to retain his humanity despite the immense burden of his experiences. The series combines fast-paced battles with moments of quiet reflection, creating a dynamic exploration of its protagonist’s evolution and the world he inhabits.