[otrs] How to add new language?

I'm trying to add new language on current cvs version. I added jp.pm to Kernel/Language. I also added new language $Self->{DefaultUsedLanguages}->{jp} = 'Japanese' to Config.pm. After that, I can find new language on the agent login page. But, there is no new language record in mysql language table. The admin interface (AdminArea ->> Language) was disappeared. How to add new language to language list at agent preference page? Best, Murahashi