最終兵器勇者　～異世界で魔王を倒した後も大人しくしていたのに、いきなり処刑されそうになったので反逆します。国を捨ててスローライフの旅に出たのですが、なんか成り行きで新世界の魔王になりそうです～@COMIC

Synopsis

Ten years have passed since four boys and girls were summoned from another world and defeated the Demon King. Arsal, a former hero who saved the kingdom and now serves in the royal army, finds himself falsely accused of a crime he didn't commit. The king, blinded by peacetime complacency, ignores Arsal's calm reasoning and mocks him as a useless burden, completely forgetting his heroic deeds. Fed up with such foolishness, Arsal abandons the kingdom, grabs his severance pay, and sets off on a carefree journey to enjoy a slow life. However, his overwhelming power makes the world see him as a dangerous threat aiming for world domination!? "Fine then — extinction it is."