Is this actually legal in Japan, having children work at a restaurant/cafe and serving the customers? Even if it is legal, does it make business sense? Sure some customers will find it charming, but it would be hard to trust they would be competent and perform their functions correctly. Also as they are young, you have to deal with mood swings that will certainly come up. Children have a much harder time keeping their emotions in check and staying professional. It would undoubtedly affect their work.