Densetsu no Ryuusou Kishi wa Inaka de Futsuu ni Kurashitai: SSS-Rank Irai no Shitauke Yamemasu!

The one who defeated various ranked dangerous monsters, the one who sealed 6 demon lords, the one who is onlooked by God. Elm, the dragon knight who wields several legendary equipment, humanity's strongest man, has continued to work for the Bangs kingdom. He accepts SSS-Rank requests, but he is mocked with the name "Subcontractor Knight." He continues this harsh labor, until his dragon partner, Baha, suggests for him to retire. So Elm and Baha depart for an unknown location to start their slow lives...

(Source: Square Enix, translated)