JIS screwdriver-- what size?

I have several old tamas, including my beloved original childhood one, that have the dreaded stuck and/or stripped screw issue. I've read about using a JIS screwdriver, but for the life of me I can't find any posts mentioning which size to use. I'd really rather avoid having to buy an entire set to test sizes. Can anyone tell me which size specifically fits the vintage tamas? Thanks in advance!

It's a size zero (#0) JIS screwdriver.

Perfect, thank you!

I just wanted to say that I did go ahead and buy a JIS #0 screwdriver, and it came in the mail today. It worked perfectly, it got the screws out of my original P1 that I got probably 15 years ago. I didn't think I'd ever be able to get the battery cover off so I could use it again, but this screwdriver did it! It also took the screws out of a P2 I have. Unfortunately I have two others that I wore the screw heads away years ago with a phillips head screwdriver, and the new screwdriver could do nothing for them....but it's amazing for the ones with intact screws, and I'm so excited that I can use my original tamagotchi again! Thanks again Ichiro!