There is a man called the "Manager." Making a living by doing businesses in the underworld, he is also known by his true identity "Dark Shipper." At the request of his clients, he provides a "thorough management" to their targets, after making them into an "obedient product", they are shipped to his clients.
Even though he had just finished a request recently, there is no time for him to rest. This time, a request arrives from the first son of a certain famous and wealthy family, to infiltrate a wedding reception which also serves as an inheritance announcement event.
The objective is to beat a spy sent by the second son of the family who is not pleased with the inheritance and plans to disqualify the first son from the inheritance rights. Basically, to the make the second son lose his rights.
If it was just a request to beat the spy, he would have turn it down, but after seeing the spy's profile, he decides to accept it.
"Kururugi Shouko"
Accepting an unusual request, the "Manager" prepares himself, setting his sights on his new target.