There is a
Japanese game tag. But it's often used because the game looks Japanese-ish, not because (as the tag is meant for) it actually does originate from Japan. Depending on the game and the translation it might have
switchable languages. A fair few of the Japanese Unity games
labelled as MTL only have a online translator installed that can be just turned off.
As moskis said there's the translation section here, or site's like
You must be registered to see the links
for untranslated Japanese games.