Kenshin to Matei no Musuko wa Date ja Nai

The world's most skilled sword god (♂) and witch empress (♀), who had saved people many times, fought fiercely in order to test each other's strength. And then, when all of a sudden they decided to marry, they suddenly disappeared. Three years later, in the Demon Forest, which is said to be the graveyard of adventurers, there were a couple and their son, Ryuku. Having inherited his parents' talents, Ryuku sets out on a journey alone.

Strongest x Strongest = Super Strongest!!! The fantasy adventure of a boy with unnaturally strong powers starts here!

(Source: Shueisha, translated)