"Don't call me "Onii-chan" anymore. You're my girl." --"Inu" is the name of a human being who was bred to be useful to society. However, they are treated as a negative legacy of society... Himuka rescues Mikoto, who was being trafficked as a lapdog, and under a "family pact" takes her in as his sister! At first, they love each other as family, but as Himuka watches Mikoto grow up beautifully, the line between brother and sister becomes blurred... The male instinct is irrepressible!　The more he puts up with it, the more they accelerate their echigo-chi relationship... A sweet and sweet H story of a doting and carnivorous brother and a wanton sister!