Notepad++ Japanese.

1. Installl npp.5.0.beta.bin as usual
2. Download Japanese language pack.
Notepad++ 4.0.2 用日本語ロケール
http://homepage3.nifty.com/georgei/extension/notepadpp_jpl_v09.zip
3. Extract nativeLang.xml to npp.5.0.beta.bin\
4. Restart notepad++
5. From menu: Format -> UTF-8