Unsouya no Ossan ga Nazeka Fukugyou de Zettai Muteki Kenshi wo Tsutomeru Koto ni ~Saenai Jinsei wo Okutteta Ore ga Maou Toubatsu no Kirifuda ni?~

Jack is a boring middle-aged deliveryman leading an ordinary and uneventful life, until one day, he's suddenly called to the royal capital. Having no idea what he's done or what's in store for him, Jack heads to the capital, but waiting for him there was...!?