S-Rank Monster no "Behemoth" dakedo, Neko to Machigawarete Elf Musume no Pet toshite Kurashitemasu, Senki to Yobareta Otoko, Ouke ni Ansatsu saretara Musume wo Hiroi, Issho ni Slow Life wo Hajimeru: Innocent Days Recommendations
Both plotlines involve legendary characters raising a kid who is also a genius. Both are very wholesome family manga in fantasy settings.