i think that the battery dimensions are identical in both versions its just a different type of battery and a less mAh
Jap battery is a LiPo and RoW battery is LiIon.
If I had to guess, to get under the 200g weight in a 2S configuration. Presumably using 18650s would make it too heavy.Any idea why they did that?
I'm pretty sure the Japanese version is 2 cell, but lighter cells with less capacity. I can't otherwise see having two versions of Mini with different input voltages.
1S = 3.7v average
2S = 7.2v average
However it's possible the battery latch is narrower for the Japanese version so that you can't use a non-Japanese version as the blocks would block full insertion.