In current implementation, 'japanese-iso-8bit' is used as prefered
coding system when you select 'Japanese' as language environment on
Unix system. But nowaday a lot of Japanese Unix users adopt
'ja_JP.UTF-8' as locale setting. So I propose to change prefered
coding system from 'japanese-iso-8bit' to 'utf-8'. And while I'm on
it, comment is fixed to fit current implementation.