Many of the older IJAAF and IJNAF types of the '20s and early '30s were given to civilian operators once they were replaced by more modern types. Once such Navy type was the Navy Type 90-2-2 Reconnaissance Seaplane or Nakajima E4N2 with the civilian registration J-BABP.
As I'm sure you know, fish play a very important part in the Japanese daily cuisine and consequently the Japanese fishing industry is of vital importance (more on the subject, here). Locating fish in the vast Pacific ocean is a tricky business even with today's technological developments. 60-70 years ago was even more difficult and therefore the experimental fishery station in Shizuoka put into use a Nakajima E4N2 which was named "dai 9 giyugo" ("giyu" can be translated as "loyalty and courage"). Interestingly the particular seaplane was modified to carry a crew of three (the military E4N2 had a crew of two), pilot Terakawa, radio operator Ebihara and a fisherman who was to spot the large fish schools of bonito. Bonito is a fish that is plentifully found in the sea around Japan using the spots where colder and warmer water currents meet as well as travelling around bigger islands. The biggest bonito fishing spot in Japan is the Tohoku region (the area where the disastrous earthquake and tsunami hit in March 2011) and the second is the area starting from Shimizu, where the airplane hangar was located, continuing towards the Izu Peninsula and all the Izu Islands.
When the fisherman/observer spotted the schools of fish, the radio operator transmitted a detailed report with the fish movements about every 20 minutes to the fishery station and also placed a map with information in a can which he threw from the plane to the passing fishing boats.
Below is a collection of photos from a vintage magazine describing how the aircraft assisted with the fishing.
At the end of the day's operation the floatplane is carried back to the hangar. The scantily clad crew member is wearing traditional Japanese underwear called "fundoshi".