A recent turn of events means that currently the majority of the users of this extension are from Japan. It makes sense then that the copy is translated to Japanese.
Todo
Find all copy and add localisation files
Work with someone who knows Japanese
Add Japanese translations
Translate the web store description (use article as a guide of what to say)
Ensure characters work well in bookmarklet titles (I've stress tested with Chinese characters so I think it should be fine, but always good to double check)
Summary
A recent turn of events means that currently the majority of the users of this extension are from Japan. It makes sense then that the copy is translated to Japanese.
Todo