So basically I found out the solution. You have to make an account with Nintendo that is the region of the game (Japan) then go to the switch and add a new user then link it to that account that is the Japanese one and its done. I was able to download the DLC of the Japanese game using the Japan user I created. Now I can go back and get all the eshop points from other games I have that is Japanese too.
This way works for me and hopefully it will work for someone else. If this is old news sorry, its New news to me.