Is there a way I can search up (filter) specifically Japanese manga instead of manhwa and ...

Your best bet is using the search feature where you can tick off the genres and simple make sure "webtoons" is crossed out
Assuming manhua falls under that category on here but even if it doesn't at least it's way more filtered and easier to spot.
Manga in general is easier to differentiate from manhwa/manhua

Thanks will try that!