Ah, but much of the original source and documentation for Ruby had Japanese section or was much more comprehensive in Japanese. This was even more true for early Ruby libraries - I can testify to it as of 2001-2003 when I was maintaining several English language libraries and writing a chapter for one of those unfortunate Syngress compilations (I was young and bad at saying no). If you're conflating Ruby and Rails, yes Rails is pretty much English-only - but though it's a common mistake, it's dead wrong if you're discussing actual languages. Even now I occasionally run into libraries with significantly longer Japanese documentation by character count and given relative density that probably means quite a lot longer in terms of actual content.
