From Naono Holics Scans:

Yukumina is from a merchant family, and as such travels the world to trade, together with his assistant Gvido.
Except, Yukumina cannot use any magic whatsoever, even the most mundane variety that's a given in his trade, and Gvido is an incubus, magic folk, widely seen as little better than the animals and monsters that populate the wild forests.
What kind of life will they manage to build together, when the world sees both of them as lacking...?