Most people in Japan keeps a hamburger in the wrapper while eating it so that the burger won't move to the side when you bite as well as your finger won't get messy with sauce (this time rice.)
Can I just say, that you guys are bringing me some kind of healing! I am in the states and I am often the one who needs to know English - English good enough to be understood. But you guys are living in Japan and are admiring what Japan offers. Love that you enjoy every bit of it. (Maybe not every bit of it bc japan can offer crazy customs as well😂) but it makes me happy to see the goodness here