The world’s most feared hitman, Taro Sakamoto, vanished from the underworld five years ago. Once a legend who struck terror into the hearts of criminals, he has since retired, married a convenience store clerk named Aoi, and had a daughter, Hana. Now running a small neighborhood shop, Sakamoto has traded his muscular physique for a flabby dad bod and sworn a solemn oath never to kill again.

This peaceful existence is shattered when Shin Asakura, a young assassin with telepathic abilities and a former subordinate, tracks him down. Sent to force Sakamoto back into the life, Shin instead finds himself on the receiving end of a humbling defeat. Seeing the genuine love and warmth of Sakamoto’s new family, Shin defects, choosing to work at the convenience store under his mentor’s strict no-kill rule.

The quiet life of the store is short-lived. A massive bounty is placed on Sakamoto’s head, drawing a rogue’s gallery of eccentric and deadly assassins eager to claim the prize. To protect his family, Sakamoto teams up with Shin and a growing crew of allies. These include Lu Shaotang, a hot-headed martial artist and daughter of a murdered Chinese mafia boss, and Heisuke Mashimo, a kind-hearted but perpetually broke sniper accompanied by his pet bird, Piisuke.

As they fend off attackers in spectacular battles that turn grocery items into deadly weapons, a larger conspiracy emerges. The attacks are connected to a shadowy figure known as Slur, who is orchestrating a violent purge of the assassin world. To survive, Sakamoto must confront his past ties to the Japanese Association of Assassins (JAA) and its elite group of the world’s twelve greatest killers, known as the Order. The season follows Sakamoto as he balances the mundane humor of running a store with escalating threats, from a high-speed fight on a roller coaster to a deadly game of cat and mouse in a haunted house, all while trying to keep his promise of peace for the family he loves.