At 52 years old, Saenai Hideo is the very picture of a defeated middle manager. As the head of the Third Sales Division at Fujiko Construction, he is routinely disrespected by ambitious subordinates like Ikesugi and overlooked by his optimistic boss, Minoshima. His home life offers no respite. His wife Enko is a domineering force who rules the household with an iron will, while his teenage daughter Haneko treats him with contempt and his young son Moyao openly mocks him. Trapped between professional stagnation and domestic servitude, Saenai has long since abandoned any hope of excitement or recognition.

This grey existence is upended when a strange, persistent old man forces a bizarre blue bodysuit into his hands, asking if he wants to become a superhero. Believing the man to be a nuisance, Saenai tries to walk away, only to watch in stunned silence as the stranger flies into the sky. He soon finds himself in a familiar predicament: his wife demands he deliver a forgotten lunch to his daughter’s school, but an important work meeting is only thirty minutes away. Desperate and out of options, Saenai dons the suit. To his astonishment, it grants him the power of flight, super-speed, and incredible strength. He completes the errand and returns to the office just in time, feeling a rare surge of relief.

However, the old man vanishes, leaving Saenai stuck with the suit. He soon discovers an unwanted side effect: he can now hear psychic cries for help from people in distress anywhere in the city. His attempts to ignore the pleas fail, forcing the reluctant salaryman to constantly slip away from work and family to perform heroic deeds. The suit has another peculiar feature: a "forgetting beam" that erases the memory of the superhero from every witness immediately after a rescue. Consequently, the local police, led by the boastful and clueless Detective Koike, take full credit for all of Saenai’s hard work.

As Saenai stumbles through his double life, the initial novelty of using his powers to skip crowded trains or quickly scrub the bathtub wears off. He begins to feel the crushing weight of responsibility, realizing that being a superhero is just another exhausting, thankless job. Just as he decides to abandon the suit for good, a crisis hits too close to home. A barricade and hostage situation unfolds at Haneko’s high school, and his rebellious daughter is among the students trapped inside. Forced to choose between his desire for a peaceful life and the safety of his family, the ordinary salaryman must finally decide what kind of hero he truly wants to be.