Kuro, a black cat, is saved by a kindhearted woman, whom he now calls his "master". Determined to help his master, who is constantly overworked and depressed, Kuro transforms into a human. As they share a home, Kuro starts to develop feelings beyond just gratitude.
The story follows Kuro, a rather oblivious cat, as he discovers his own emotions. He acts on his primal instincts and becomes increasingly assertive towards his master.