Sakamoto Days Vol. 1 (manga)

Taro Sakamoto was once a legendary hit man considered the greatest of all time. Bad guys feared him! Assassins revered him! But then one day he quit, got married, and had a baby. He’s now living the quiet life as the owner of a neighborhood store, but how long can Sakamoto enjoy his days of retirement before his past catches up to him?!

Time has passed peacefully for Sakamoto since he left the underworld. He’s running a neighborhood store with his lovely wife and child and has gotten a bit…out of shape. But then one day a figure from his past pays him a visit with an offer he can’t refuse: return to the assassin world or die!