Itsudemo Jitaku Ni Kaerareru Ore Wa, Isekai De Gyoushounin O Hajimemashita

"Won't I be able to get filthy rich if I use this skill?"
Continually exploited at work, Amata Shirou quits his job and moves to his grandma's house.  When he finds out that it's connected to another world, he comes up with a plan to set up a business selling Japanese goods.
The story of a man getting rich using his skill that converts the currency of the other world to Japanese yen and so forth.
I Can Always Go Home, so I Started as a Peddler in Another World
Peddler in Another World: I Can Go Back to My World Whenever I Want
いつでも自宅に帰れる俺は、異世界で行商人をはじめました