Kazuki was a ex-vigilante in his universe. In the past he and his siblings Yuki (big sister) and Kazumi (little sister) was a group of vigilante called the "Cursed Childs". This group was created to avenged their parents death who killed by a group of terrorist who want to kill all humans lead by a strong vampire clan.

​

After avenged their parents death, Kazuki married to a girl named Yukine Suzu who they stayed together since childhood. One day, a weird unknown portal suddenly appear in their house. Kazuki and Suzu shocked and suddenly a weird figure with white cat ear hoodie came out from the portal. He seems to be confused with the dimension that looks different than his dimension. Kazuki and Suzu confront the figure and asked him what is he doing. The figure said he was currently looking for maid, butler, bodyguards for his family. So he use his son's portal and ended up appear in their (Kazuki and Suzu) house. Since both Kazu and Suzu currently unemployed and kinda in tight situation where they kinda in need to find a job so they both agree to work for them. So they ended up become the Royal Guards of the Tadano and also become Maid and Butler and also a Babysitter for some reason.

​

Kazuki got a alternate form where he borrow his little sister (Kazumi) body. But, after joining the Tadano family, he was given a curse form named Kaju.