Master spy Twilight is tasked with infiltrating the elite Eden Academy to prevent a war between rival nations Westalis and Ostania. To pull this off, he adopts the persona of psychiatrist Loid Forger, hastily assembling a counterfeit family that includes a sweet-natured telepathic girl named Anya as his daughter, and a lethal assassin named Yor as his wife. Unbeknownst to each other, all three members are harboring deep secrets while striving to maintain the illusion of a normal domestic life. As the mission unfolds, the trio navigates the hilarious and chaotic waters of everyday family life while dodging enemies, school entrance exams, and undercover threats. Despite being brought together by convenience and deceit, Loid, Yor, and Anya gradually develop genuine affection for one another, blurring the lines between their fabricated roles and a real family.