Mannen D-Rank No Chuunen Boukensha, Yotta Ikioi De Densetsu No Ken Wo Hikkonuku

Lucas has a hard life. In his mid-thirties, a mixture of failures has left him old and crippled, playing pack mule to a couple of young adventures. Then one day, he pulls a magic sword from a stone that tells him he has been chosen to become a hero. Given a youthful form, Lucas must use the power of the sword to vanquish evil and attain a massive harem. Before you ask, it’s not isekai because he’s been in this world from day one. It is wish fulfillment, though, so in the end it’s basically the same thing.