The story centers around the young linguistic genius and university professor Testa. He is introduced by his senior, Sergeant Rossa, to the Allied Cryptanalysis Department. There, he is tasked to break the enemy werewolves' code, which the werewolves are using to encrypt their radio transmissions. Testa is astounded, as the only sound the encrypted code produces is the howling of a wolf. His research yields no results, and he resolves to capture a live werewolf for better cryptanalysis. After exhausting all possible means, he finally finds a female werewolf, Yonaga.