Gai Kurasawa, a private detective, and his partner Kiko Kayanuma, a young girl, are hired by the widow of a cosmetics company executive to search for her lost black cat. On multiple occasions, Kurasawa ends up bumping into Hei, who is on the search for the Contractor killing employees from the very same company, making Kurasawa begin to be suspicious of Hei. Kurasawa then accidentally takes the jacket of that Contractor, although he hasn't realized it, while on his way to a house upon the suggestion of his client. There, he finds a black cat (Mao) and captures it, but also unexpectedly comes across the skeleton of a long dead woman.