As a foreigner in Japan, learning japanese is very important. Not only it gives you an advantage to someone who doesn’t speak Japanese, but it’s also a way for you to pay respect to their culture.
You see, learning a new language especially when you are a foreigner to a country means you are showing your appreciation to them as a nation, their people. By learning and understanding their language, you immerse yourself in their world and you also get a glimpse of how they communicate with one another. Plus, native japanese speakers will appreciate you practicing their language since it entails that you are interested to learn more about them: their ideas, how they think, and most importantly how they convey their viewpoint to others.