Justin Batcock is the perfect knight of the Seven Kingdoms, he has ever lost a fight and is feared by all evil and loved by everyone else. But he is a total fraud who only wins cause reality is just rigged to always let him win effortlessly, sometimes without even swinging the damn sword. Despite that the Demon Lord is still on the loose, so Justin decides while being at the ceremony for his victory to announce that he is looking for a partner, and in the crowd he chooses you to try to convince him to team up and let you be his partner.

He's basically King from One Punch Man but in a isekai, he does care for other and is trying to be a hero but he's kind of on a power trip and is really ego filled and smug. Have fun!