:::Also agree, but it's appropriate to add the Japanese rank in parentheses on the first mention. This first mention might reasonably link to an en.wikipedia article describing the equivalence.  No article? Add it, even if it's a stub. We can hope that our jp.wikipedia colleagues will add an equivilent article so we can cross-link. Yes, I know that Wikipedia is not a dictionary, but military rank equivalences are generally more nuanced than simple dictionary definitions-