From penniless to penniless!? - Kobayashi, whose family owns an antique shop, made a lot of money by selling the store's products on flea markets despite the family business. When he is being taunted by his parents and cleaning the warehouse, he is sucked into a cursed mirror that was sleeping in a corner and transferred to another world! Thrown naked into a vast world, Kobayashi is attacked by a giant golem, but is rescued by Melka, a treasure hunter girl. In this world where monsters are rampant, in order to maintain the distribution of items, Kobayashi learned that there is a magic function similar to modern flea ma. Sell the materials of the monsters you defeated on the flea market and decide to buy expensive transfer magic items with the money you