Absolutely, please keep Japanese output the way it is - it's the only approach that makes sense. Romanization loses a lot of information and makes things harder

Absolutely, please keep Japanese output the way it is - it's the only approach that makes sense. Romanization loses a lot of information and makes things harder (except possibly for the absolute beginners), not easier. However, it'd be extra cool if there'd be an option to display furigana - in case user had forgotten or doesn't know some particular kanji. Or maybe just throw an option to replay the audio.