I've been working with a Japanese company who chooses to encode our files with EUC-JP. I've been curious for quite a while now and tried asking superiors why EUC-JP over SHIFT-JIS or UTF-8, but get answers "like it's convention or such". Do you know why the initial coders might have chosen EUC-JP over other character encoding?
Unlike Shift-JIS, EUC-JP is ASCII-safe - any byte where the eigth bit is zero is ASCII. It was also historically popular in Unix variants. Either of these things could have been an important factor a long time ago before UTF8 was generally adopted. Check the Wikipedia article for more details.