The story follows a spy who has to "build a family" to execute a mission, not realizing that the girl he adopts as a daughter and the woman he agrees to be in a fake marriage with are a mind reader and an assassin.

For the agent known as "Twilight," no order is too tall if it is for the sake of peace. Operating as Westalis' master spy, Twilight works tirelessly to prevent extremists from sparking a war with neighboring country Ostania. For his latest mission, he must investigate Ostanian politician Donovan Desmond by infiltrating his son's school: the prestigious Eden Academy. Thus, the agent faces the most difficult task of his career: get married, have a child, and play family.