When Saku took in a stray black cat, she never expected that he would become the equivalent of a housekeeping life partner. But Yukichi, a giant cat who towers over Saku, is not your ordinary feline. He takes great pride in his culinary skills, and a good sale at the supermarket always gets his whiskers twitching. Saku may not have her act together yet, but at least she has Yukichi!

This science fiction omnibus depicting a doctor who "treats" robot and humanoid problems takes place in the near future, when humanoids with artificial intelligence account for 10% of the population. The main character, Dr. Sudo Hikaru, also has the undercover name Moggadeet, under which he secretly takes on illegal medical procedures. For example, for a man who inadvertently infected his humanoid wife with a computer virus when illegally backing up her data, Sudo proposes an operation to rewrite her memory using backup data. Could an existence replaced by backup data truly be said to be the same as it was before?

The end of the 19th century—a vampire's wife is murdered, and the detective known as the "cage user" is called in to solve the crime. But there's more to the detective and the curtained birdcage he carries...after all, when solving a case involving a monster, it might just take one to know one!