Erina Wada has no trouble being composed in the company of her classmates, but the moment she lays eyes on a cat, she regresses into a cooing, googly-eyed mess. Therefore, it is no wonder that when she spots a cat in danger in her backyard, she jumps to rescue it without a second thought. What follows is a thorough cuddling session as Erina fawns over the sheer cuteness of the cat. However, as she raises the cat to her lips and kisses it, the cat morphs into a man who is stark naked. Overcome with shock, Erina faints.

After regaining consciousness, Erina shrugs off her earlier encounter as nothing more than a dream. So when the same cat visits her and kisses her without warning—turning into a man again—Erina is too stunned to react. Adding to her already growing confusion, it dawns on Erina that the man is Kou Nekoyama, an unsociable boy from her class. As unfazed as ever, Nekoyama declares that Erina is now his master—leaving her in a state of disarray.

What will come to be of this strange arrangement between a high school girl and a mysterious shapeshifter?