Not sure if this has been discovered before, but https://www.reddit.com/r/Megaten/comments/9yaaf3/i_found_the_full_japanese_box_art_for_jack_bros/

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   yd3p0ogfw5z11.jpg
   

Awesome – they scanned it as well for people I believe, I can’t be certain I find Reddit really awkward to navigate to be honest.

L___E___T wrote:
Awesome – they scanned it as well for people I believe, I can’t be certain I find Reddit really awkward to navigate to be honest.

Me too, I only found this because it showed up in “Articles for you” on Google lol