Corrected some Japanese translation

[t33pa]

Hello! I found this website the other day and I thought it was an awesome project-featuring website. Sent this PR because I found some of the jp localization in this website a little bit off to me, so I edited the jp locales. (my native language is Japanese) In most part of this PR, I have just corrected the translations, but I might translate the untranslated part of this website with another PR in the future.