As part of a class called "Marriage and Family", Ji-woo is given the opportunity to meet new people through a dating assignment . Unfortunately, though, there are more male students enrolled in the class than those of female, so Ji-Woo is ultimately forced to choose a male partner against his will. It is at this point that Ji-woo encounters his soon-to-be tall and handsome partner, Roa.

In a dystopian 2071 devastated by air pollution, the survival of humanity depends on the Black Knights — and they’re far from your average delivery men.