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?! A young Sakamoto and his classmates' mission to assassinate Kindaka goes sideways, and they now find themselves somehow working with their intended target to protect some VIPs from an assassination plot. They later learn that Kindaka is part of a special assassination group known as the Order! Can they survive the onslaught of hit men that lies in wait?!