Theres 2 types of these type 97 machine guns.
The Tank mounted Type 97 LMG that we have in the game
Then there is the aerial type 97 machine gun thats usually mounted into the cowling of the A6M Zero. It was also hand held by japanese infantry in some cases. Its essentially A licenced copy of the Vickers Class E machine gun, firing a 7.7 mm x 56 mm rimmed round. Could be another Tier V weapon for Japan.