The watch is quite unusual and obviously runs at a very high beat. The top small hand indicates what ring of numbers to read when the unit is stopped. I have not seen one before, but like the phonotelemeter, Seikosha has produced numerous hi-beat military measurement instruments but these are not often seen.
I believe these Seikosha stopwatches are quite rare. Very few of the Type 97 drift sights survived the war.
Ill bet the Aichi Seirans Type 97 drift sight at the Dulles museum is even missing the Seikosha stopwatch. Watch has been recently serviced and is running great. See photos for case and movement condition.
The item "Rare WW 2 Imperial Japanese Navy Seikosha Type 97 Drift Sight Stopwatch" is in sale since Monday, August 19, 2019. This item is in the category "Collectibles\Militaria\WW II (1939-45)\Original Period Items\Japan\Other Japanese WWII Orig Items". The seller is "mrcorf" and is located in Sarasota, Florida.
This item can be shipped to United States.