It's pretty common knowledge that people use chopsticks to eat in Japan. However, fewer people are familiar with the customs surrounding chopsticks and eating. If you're a tourist visiting Japan and you happen to find yourself eating a meal with chopsticks, try to avoid stabbing your food with chopsticks if you aren't used to using them yet. This is because it can be seen as rude to use your chopsticks like a fork.
Instead, hosts and other diners will be far more appreciative that you're at least trying to learn how to properly use chopsticks, even if you're not fully perfect with them yet.