This is a decoder for JJEncoded string. I hope it's useful for someone out there. JJEncode is originally made by @hasegawayosuke - http://utf-8.jp/public/jjencode.html

Here is a detailed analysis of how it works: http://pferrie2.tripod.com/papers/jjencode.pdf