His Playmate by Ace Fawn

One mistake has twisted Diego Montosa’s world into darkness.

He kidnapped Wolf Lone’s only son, and the same thing has now happened to him.
Diego has been taken captive by an irresistible yakuza boss, broken down, and turned into his personal plaything …
Wolf is ruthless, subjecting his new pet to painful punishments and addictive pleasures. But Diego is a vicious young gang leader and will rebel at every chance he gets … even if it means sleeping with the enemy.