Nippon or Nihon?

Tweet

Japan in japanese language is either Nippon or Nihon. I just wonder why is it so. Japanese language is nihongo but some says it is nippongo. Japanese people who could speak in english say that it is only nihongo and they do not use nippongo. Japanese(people) in japanese language is nihonjin and not nipponjin. By the way, the "go" in nihongo means language therefore when "nihon" and "go" where joined toghether, it is nihongo, the japanese language. The "jin" means people, so "nihon" plus "jin" is nihonjin, japanese people. But japanese people tell that they don't use "nippongo" and "nipponjin" in their language but they use either "nippon" or "nihon" for "Japan". Confusing? Well, I am also confuse. Which is which. Ganbare Nippon! That is their cheer! I seldom or perhaps never heard "Ganbare Nihon". So what do you think? Nippon or Nihon?