I think the honest truth is that Japanese is the ultimate challenge of any translation too.

My Japanese friends tell me that DeepL is about as close as you will ever get to a passable translation quality.

But DeepL does not do image translation.

On a recent trip to Japan I installed six image translation apps on my phone.

None were perfect, I found Naver Papago to be the most consistently usable (although it was far from perfect).

Interesting observations I made during the extensive testing:

     1) The majority of image translation apps don't like Japanese when written vertically, I found they perform best with horizontally written Japanese.
     2) All image translation apps *REALLY* don't like hand-written Japanese.  Some of them *MIGHT* translate *SOME* of the text. But really all of them only really work consistently with machine-printed text.