Hotaru Kusakari is married to Gorō Kusakari, and she works as a pharmacist. She holds a secret that she is really a ninja and part of the Kōka ninja clan. Her husband holds a routine job as a postal delivery man, but he has a secret as well. He is also a ninja and part of the Iga ninja clan. Even though Hotaru and Gorō are a married couple, they are each unaware that their partner is a ninja.