This "modified type 97 tank MG" probably came from the type 2 Ka-Mi amphibious tank destroyed or captured on Saipan, according to this https://t.co/fHNDuDnN4y document.
Type 2 Ka-Mi does have a coaxial Type 97 MG I think?(Pardon for using English...) https://t.co/RnonULlV89