looking for this manga

Hi! I read this manga like years ago, and if i remember correctly it was set in a fantasy world and MC (dark hair, stereotypical japanese shounen protag) was the hero of the kingdom/place (i cant remember if he was a hero that was "summoned" here, or if this was a video game setting and he is just a super strong player). i believe the manga format shows like a status bar looking thing for that has skills and whatnot.

manga starts off with a large fight between MC and this final boss looking dragom thingy, and mc was on a ship/harbor thing??? and i think he had strong allies, too. i think after he defeats it, mc retires or smth, but the gist is that he disappears and the story rlly starts when he kinda returns. does anyone know what im talkimg about?