The narrative focuses on Testa, a young linguistic prodigy and university professor. His superior, Sergeant Rossa, introduces him to the Allied Cryptanalysis Department. There, he is assigned to crack the enemy werewolves' code, which they use to encrypt their radio transmissions. Testa is stunned because the encrypted code produces only the sound of a wolf howling. His research proves fruitless, so he decides to capture a live werewolf to aid his cryptanalysis. After trying every possible method, he eventually locates a female werewolf named Yonaga.