Technically correct is the best kind of correct

Proper solution does not exist as Ruby does not know ISO-2022-JP-2.  So
instead of String#encode you should call 'iconv'. I could have
monkey-patched String to use iconv, but it's still stupid, when you
should call it directly or refine String in your module scope

Also regexp makes little sense String#each_char.size > 0 might be
better.