"Encyclopedia of Japanese Aircraft" vol. 3 indicates that this particular flying boat was a Navy Type 97 Transport Flying Boat or Kawanishi H6K2-L. I'm not 100% sure because the windows in the nose are too few and square, not round, shaped which is indeed an indication of an H6K2-L but no windows are visible in front of the fuselage side door; if they were there they would fallen on the hinomaru. Perhaps the wing float is covering them. Note the absence of side blisters, another transport indication.