The exoneration of former death-row inmate Iwao Hakamada has been in the news lately:

http://www.npr.org/blogs/thetwo-way/2014/03/27/295162651/sentenced-to-death-46-years-ago-japanese-man-is-now-free

For an audio podcast (and text transcript) about this case see

http://www.npr.org/2014/04/06/299708675/japan-releases-inmate-after-nearly-half-centure-on-death-row

This first person to be exonerated in this way was MENDA Sakae of Kumamoto in 1983:

http://en.wikipedia.org/wiki/Sakae_Menda

There has still been only a handful of such exonerations in Japan.