The story revolves around Taro Sakamoto, a retired legendary hitman who has settled into a quiet and mundane life as a family man.

To protect his family and loved ones, Sakamoto must use his exceptional combat skills to face off against a variety of adversaries while trying to maintain his ordinary facade.

An anime television series adaptation produced by TMS Entertainment premiered in January 2025, with a second cours set for release in July of the same year.

Sakamoto agreed, and after his retirement they started dating, got married, had a daughter named Hana, and eventually opened a family-run convenience store of their own in the suburbs of Tokyo.

The world of hitmen eventually locates him, and many soon attempt to target the Sakamoto family, either seeking revenge or resenting his retired status.

The concept of Sakamoto, a highly skilled individual whose abilities are masked by his unassuming appearance—a result of his married life—served as a key inspiration for Suzuki.

He was particularly intrigued by the idea of a strong, obese fighter, a notion that was partly influenced by the comedic action film Enter the Fat Dragon.

Although Suzuki acknowledges that his characters can sometimes be difficult to distinguish visually, he found Gaku to be the easiest to draw due his independent personality.

Watanabe highlighted Sakamoto's distinctive personality and calm daily life, which create a striking contrast during action sequences involving his obese physique.

Reflecting on the narrative, Watanabe noted that despite its comedic foundation, the series occasionally delivers unexpected moments of violence, an aspect he found particularly commendable.

[4] Despite his experience with shōnen manga, Watanabe found Sakamoto Days to be a unique challenge, as he aimed to balance intense action sequences with the lighthearted tone established by Suzuki.

Watanabe primarily utilized Clip Studio Paint and Adobe for production, incorporating a paper texture to enhance the visual style of the action sequences.

It is directed by Masaki Watanabe [ja], with scripts by Taku Kishimoto, character designs by Yō Moriyama, and music composed by Yuki Hayashi.

[26][27] A promotional video for the manga's eighteenth volume, starring Saori Izawa [ja] in the role of a store clerk, was released on August 2, 2024.

She ended her review with: "If some of the later chapters aren't as tightly executed as the first, Sakamoto Days nonetheless achieves a good balance between character development and karate-chopping.