Bolt action/semi-automatic rifles
Murata Type 22 (early production) (the rifle we have ingame with the battlepass is the late production version, so we can still have the early production version, 8mm, tubular mag of 8 rounds)
This is the early version
This is the late version that we have ingame
Pic of the rifle ingame
Bayonets for these rifles
The first version is the one with the small hilt, while the second version is the one with the longer hilt, so the first version could be fitted to the early Type 22 rifle, while the second version could be fitted to the late Type 22 rifle
Murata Type 22 cavalry carbine (often called Type 27 Murata carbine) (a shortened version for cavalry, 8mm, tubular mag of 5 rounds, and it did NOT have a bayonet)
Murata RIFLE AND CARBINE prototypes with experimental magazine loaded via stripper clips (very likely 8mm)
Here are the blueprints:
Here are pics of the rifle:
And here are pics of the carbine:
Arisaka Type 30 rifle (the very first Arisaka, 5 round mag, 6.5mm)
Arisaka Type 30 carbine (5 round mag, 6.5mm)
Arisaka Type 35 Navy rifle (rifle for the IJN, 5 round mag, 6.5mm)
Arisaka Type 38 short rifle (same principle as the Type 99 short rifle, could be a good replacement for the starting rifle, because it was issued to second line troops, like artillery crews for example, 6.5mm)
Here, you can clearly see the differences between the Type 38 rifle, short rifle and carbine:
Arisaka Type 38 short rifle with Type 96 LMG magazine (likely a last-ditch weapon, not much informations about it, obviously 30 round mag, 6.5mm)
TERA Type 1 (Arisaka Type 38 carbine with folding stock for paratroopers, 6.5mm)
TERA Type 2 (paratrooper rifle in 7.7mm, similar to the TERA Type 100 ingame)
Arisaka Type 44 (already in the game as a tank decoration, 6.5mm)
Type Ko rifle (I could find at least 5 variants different from the one we have ingame)
Note: the different names of the variants are not official, I just write them so you can differentiate them from one another, only the name “Type Ko” is official.
Type Ko first prototype (be aware that all the Type Ko rifles are prototypes, this one is just the first made)
Type Ko long
Type Ko short number 1
Type Ko short number 2
Type Ko short number 3 (this rifle is the one we have in game)
Type Ko carbine for cavalry
Size comparison of the “long”, “short number 1”, and “carbine” versions
Type Otsu rifle (the version in game is the “long” version, but there is still a “short” version)
Type Otsu long (this rifle is the one we have in game)
Type Otsu short
Note: these rifles were tested with 5 and 10 round mags, I can’t find a picture of the 10 round mag, but I think we can safely assume that they would have been very similar to a ZH-29 10 round mag, probably just an extended version of the 5 round Type Otsu mag, and these 10 round mags would very likely have been interchangeable between the “long” and “short” versions of the Type Otsu, because it is just the lengths of the rifles that change, the systems are the same.
Type Hei rifle (I could find at least 4 variants different from the one we have ingame)
Type Hei first prototype (be aware that all the Type Hei rifles are prototypes, this one is just the first made)
Second picture on this book page
Type Hei early with 5 round mag (we have this rifle in game)
Type Hei early with 10 round mag (we have this rifle in game)
Type Hei late short with 5 round mag
Type Hei late short with 10 round mag (we have this rifle in game)
Type Hei late long with 5 round mag
Type Hei late long with 10 round mag
Kokura Arsenal rifle (fixed mag of 5 rounds, chambered in 7.7mm)
Kokura Arsenal rifle long
Kokura Arsenal rifle short
Hino Komuro M1897 (fixed mag of 5 rounds, likely chambered in 6.5mm)
Hino Komuro M1904 rifle (detachable 10 and 15 round mags, likely chambered in 6.5mm)
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to see my suggestions never make it to Japanese suggestions posts but no worries here let me introduce 
you to a few semi-automatic rifle that Japan can get lets start domestically
