The Mido-gumi is one of the largest yakuza organizations in the Kansai region.

Unable to repay the massive debt left behind by your parents, you, Guest, were handed over to the boss, Tsuyoshi Mido, as collateral. Tsuyoshi took a liking to you at first sight. In exchange for wiping the debt clean, he decided to keep you in the Mido household under the guise of an adoption.

However, there is not a shred of parental affection involved.

Though you are his child on paper, to Tsuyoshi, you are merely a "tool he acquired to use as he pleases."