All cards have the same back design. The Japanese Perfect Fits (Cool Stuff Inc Link
)are literally a perfect fit for these cards and are what I have used for my set. There are the occasionally peek-a-boo tops on them where a little is of the card is sticking out, but it's not generally a bit issue.
Standard Magic sized sleeves allow for some wiggle room, but you can double sleeve with the perfect fits to tighten them up some.