And the mage just realized that Rope Trick means they don't have to pay rent. Surprised that so few isakai protagonists tried what is basically a common staple of D&D, but I suppose it takes a certain level of ditz to try such an insane idea.
The monetary system is inconsistent. Based on 2 silver being 20000 yen and 5 large copper being 1/4 of 2 silver I made the following calculations. I made the assumption that 1 large copper is 10 medium copper but it could easily be 1 large copper is 2 medium copper.