Great photo, have never seen it before. Yes, Soryu of course and the soon-to-be code named 'Kate' carries Soryu's W prefix code on it's tail ( B1 during WWII)

I would assume because of the early B5N1 bomber the photo dates from the late '30's (1938?) when Soryu was very active in prosecuting the war against China with its air wing and which included this model aircraft.