Japanese people will be more than happy to spread their language, literature, culture and so forth to other countries, but many will at the same time insist, that to truly understand it, you will have to be Japanese
Japan, like all countries, contains a huge variety of opinion, though in Japan, most people keep their opinions to themselves out of fear of creating social upset. There are Japanese who believe that anything Japanese can only be understood if you are born and raised there. There are others who think that Japanese things can be readily understood by non-Japanese, and there are a huge number in between the two ends.
Japan was a closed society for 250 years, and even now, 160 years after it was blasted open, most Japanese have little or no real contact with non-Japanese. It's still essentially a closed culture. That doesn't mean you can't grasp the ideas and concepts that form the base of the culture, it just means that learning to function smoothly in Japanese culture is really, really difficult. It can be done, but I'm pretty sure the reward is nowhere near the value of the effort.