Mabeopjungnyeon Ajeossi

Ace soldier Jeong Jin-Oh is given a crucial mission to save the world. But that mission is to become a magical middle-aged man!? What's more, as soon as he becomes a magical middle-aged man, his colleagues who were following him suddenly start attacking him, saying they smell good. The one who shows up to save Jin-Oh in trouble is Elia, a thorn in Jin-Oh's side and another ace in the military...?!

(Source: Bomtoon, translated)