Moving from Slackware 14 to 14.2 I forgot one or two details about how to get mplayer to display Japanese srt subtitles. At this time an essential bit is that mplayer needs to be explicitly pointed to a suitable font. I used the -fontconfig -font [fontname] solution, and put it in my .mplayer/config file.
Some options seem superfluous by now. I simply stopped experimenting when I got it to work.
subfont-encoding=unicode
unicode=yes
utf8=yes
subcp=utf-8
fontconfig=yes
font='さざなみ明朝'
Here is a copy of my mplayer config file
