Maybe something like the Otsu with a 10-round capacity or in other words, a Japanese version of the ZH-29. There were also other rifles derived from it, like the Z-37, though that one would be more likely to appear with the Germans.
I’m not entirely surprised that this has ended up as a BP weapon for Japan, and personally from everything I’ve seen here on the forum and thanks to the assistance of others, their hard work and my own research I frankly prefer this as a BP weapon.
Personally as it stands I think the most suitable choice would be the weapon suggested by @Valkay and their topic on the Shenyang Arsenal ZH rifle with a 20 round magazine.
It can’t be BR3. The ZH-29 with a 10 round mag is BR4. It would have to have genuinely horrid stats on a level that it won’t be used to be at BR3 and that’s just a waste of a BP.