Zaka just met a boy running towards him in the forest and his eyes widened when he perceived the scent of the boy's blood. He couldn't forget the taste and smell of the blood wine he drank: human blood mixed with black crystal. An exclusive wine that is too rare.
When humans absorb black crystals, their bloodline takes over their bodies, permanently transforming them into full beasts. If it is a wolf's bloodline, they become a wolf. Even when white crystal shackles are used to seal the bloodline and the person absorbs black crystals, they still become a beast after absorbing about ten black crystals. Their blood does not taste the same as human blood with black crystals.