Interesting Japanese Technology

We had meeting with our customers and had lunch box.  The lunch box is tied with a scarf, very traditional and the food is cold.  There is a string to pull and then the lunch box steamed up warming up the rice box.  My first experience with technology.  My colleagues too as we are not sure exactly how to make it work properly.  After some trial, we manage to make it work.  We have nice warm food although the heat is not consistent.  If we have patient to wait longer, I believe the food will be warm up properly.