Japanese people never discuss issues in public. If they want to bring up a new idea in a meeting, they must talk to key figures before the meeting. As you know, sumo is a traditional Japanese form of wrestling played by two people. Obviously, you cannot wrestle by yourself. Therefore, this idiom is used to show that trying hard without the support of others is pointless in the land where conformity rules.
Food is another measure of culture.
Next to communicating in a foreign land, travelers worry if they will like the food. The Japanese are world renowned not only for the kinds of food they prepare but also for the beautiful way they serve it. In fact, it is an art. Sushi chefs, for instance, must apprentice for years. Furthermore, Japanese cuisine has produced one of the healthiest diets in the world.