Following a devastating conflict that caused widespread devastation among the population, world leaders turned to a more covert approach in order to achieve their objectives-a secret war. Lily is a student at one of many institutions that prepare young individuals for espionage careers. Despite performing well in written tests, she struggles with practical exercises. With no practical skills, her chances of graduating are slim until she receives an invitation to join the enigmatic "Tomoshibi" team and undertake an unattainable mission. Enthusiastically, Lily accepts the offer, but is left in disbelief when she arrives at Kagerou Palace and learns of Tomoshibi's true purpose and dire circumstances. Along with other problematic female spies and a mysterious young man leading the operation, Lily discovers that this is not the adventure she had envisioned.
Spy Kyoushitsu placed second in the Kono Light Novel ga Sugoi! ranking in the best light novel category in 2021.The series has been published in English as Spy Classroom by Yen Press under the Yen On imprint since August 24, 2021.