Eating while walking outside is frowned upon in Japan. In fact, eating almost anywhere other than a designated eating area is frowned upon. If you've ever taken a stroll outside in Japan, you'll probably notice that nobody is eating anything. It's also very rare for the Japanese to walk outside holding coffees.

While there is no law against it, walking while eating or drinking is generally frowned upon in Japan as a matter of social etiquette (manners). Japanese culture emphasizes ikkigo, or focusing on one thing at a time; doing otherwise is seen as "messy" or disrespectful to the surroundings. Most locals will buy a coffee from a vending machine or café and consume it while standing nearby or sitting on a designated bench. You will rarely see a Japanese person rushing down a sidewalk with a latte in hand. If you do walk with a drink, you may receive subtle "glares" from locals, as it marks you as a tourist who is unaware of local norms. Furthermore, Japan has very few public trash cans; carrying a cup while walking often means you will be stuck holding the empty container for a long time. The polite approach is to finish your drink at the point of purchase or wait until you reach your destination.