Food company salesman Tokichi Inaba was once a feared hitman known by the alias Nidō, or Two-Guns. After leaving that life behind, he settles into a quiet existence with his wife Misako. That peace shatters when he is strapped to a bomb, handed a gun, and forced to carry out a deadly under-the-table job. With his own life and his family’s safety on the line, Tokichi has no choice but to return to the world of violence he thought he had escaped.

The ordeal pulls him back into the orbit of the criminal syndicate Konbini, which once employed him. Completing the forced assignment only leads to a reunion with a key figure from that organization, and Tokichi soon learns that his retirement five years earlier sent ripples through the underworld. He is once again trapped in a precarious double life: a salaryman by day, a hitman by night, juggling office work, his marriage, and the dangerous connections he inherited, including the former Nidō’s girlfriend Chinatsu.

As the story progresses, Tokichi faces escalating missions. One arc involves a high-stakes operation to recover a hard drive containing classified information; during a gunfight, he must also use his phone to participate in a company online auction. Another arc introduces the current bearer of the Nidō alias, leading to a showdown in a mountain shack. The series weaves action, dark humor, and the constant tension of a man trying to protect his ordinary life while being dragged deeper into the criminal world.