I have to mate if i want to get stronger.

As he accumulated good karma In all of his previous life , he got chances to get a better reincarnated life, but because of he didn't marry at all, a conditional for the exchanges of reincarnation was to have a child with at least a Hundred Beautiful women in the world. Each years after he can have a child, he need to mate with one girl and have a child. This will start when he was around 11 years old. He was forced to accept and reincarnated as the son of the world most wealthiest underground merchant . He thought of being powerful enough to offsets this contract, and he have all the resources from his family but there's also a lock where he can't gather energy or use other outside (world) power to increase his strength. The only thing he can use were his own power and body power that can be raised with trainings. He can't cultivate or gather mana, only left with superpower as a gift from the heavens.