Hero Manufacturing Machine ~A Job to Make Children~ Unknown

Yusharurushu Braveroad or 「Sharuru」for short is a royalty that’s also the youngest blood relative of a hero.
He has low chance in rights to succession so he willfully lived as an adventurer.
Since his nine elder brothers had died in succession, he was selected to be the stallion of the next generation heroes.
He began with the beautiful female knight(Assassin), and the unrelated widow.
He inseminated his sisters-in-law one after another.