Fable is a legendary hitman who has completed numerous jobs for a variety of clients. After concluding his latest assignment, the number of people he has recently killed becomes too high, and Fable is ordered by his boss to lay low for a year. He is suggested that having to adapt to life as an ordinary citizen might prove a valuable experience for his future work.

Fable is to be accompanied by the woman who acts as his driver, and the two will assume new identities as siblings. However, their boss warns them that they will both face a deadly punishment if Fable kills anyone during his time off. Thus begins Akira and Youko Satou's joint one-year sabbatical from the underworld.