Sakamoto Days

Taro Sakamoto used to be an unrivaled hitman, earning legendary status in the criminal underworld by being feared by some and idolized by others. One day, however, Sakamoto fell in love at first sight with Aoi, a convenience store clerk. For them to date, Aoi gave him the ultimatum that he must quit being a hitman and never kill again. 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.
Several years later, Sakamoto has settled into his humble life, but also grown portly as a result of his relative inactivity despite still being immensely powerful. The world of hitmen eventually locates him, and many soon attempt to target the Sakamoto family, either seeking revenge or resenting his retired status. Now, with the help of three other former criminals who become employed at the store under Sakamoto—clairvoyant hitman Shin Asakura, orphaned crime boss daughter Lu Xiaotang, and sniper Heisuke Mashimo—Sakamoto must protect his family (or die trying) against the criminal underworld, all while maintaining Aoi's no-kill policy.