Yeah i call bullshit on this one. Even for a Japanese protagonists this is a little much. The merchant straight up tells a modern business man that these are cups to use as gift for married couples. He either offers both cups to the demoness as a gift, or uses both as a product to be sold. They loose a lot of value when seperated. This last scene makes him out to not just be culturally insensitive, but a completely incompetent business man.