Create po file for Japanese translation.
Add rules for spec.md.ja and spec.html.ja.
Write description of po file.
Translate.
Translate.
Translate.
Translate section 1.1.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.
Translate.