A 21st-century office worker travels back to 1947 Chicago while taking a bath. A female mafia boss mistakes him for the legendary hitman “Jade-Faced Yama”, who has been missing for a decade. After a one-night stand, he is forced to keep playing the role of this cold-blooded legend, using modern knowledge to show off and humiliate rivals at every turn. Just as he gains a firm foothold and wins the mafia queen’s heart, the real Jade-Faced Yama — his twin brother — returns. And this woman has secretly loved his brother for ten long years.
