added a comment - - edited
Short answer would be yes. JRuby's 1.8 mode worked like CRuby. If I dare to say, 1.9 mode works slightly different from CRuby. To show what the difference is, I attached screenshots of both CRuby and JRuby's results (CRuby_Japanese_chars.png and JRuby_Japanese_chars.png). As you can see, JRuby returned a sequence of "\xE7\xB4\x85\xE7\x8E\x89," while CRuby did the exactly the same Japanese characters. But, the returned value from "puts" was correct even in JRuby 1.9 mode, and was the same as CRuby. I'm not sure this difference matters or not. At least, this should be another issue since ?? doesn't show up anymore. So, I think this issue has been fixed.