The Land Battle of Okinawa started on 1st April 1945, between the latitude of the Capital Naha, 26*N12'26", 127*E40'24", and Ishikawa, 26*N25'24", 127*E49'17".
At the midnight day marker we find Sirius setting in Naha, out of synch by 3 mins 42 secs, which is within the the four minute margin used by secret societies, however this is below where the troops came ashore.
Above where they came ashore we have Ishikawa and at the midnight day marker, again within the four minute margin, Sirius is setting in the West, out of synch by 2 mins 47 secs.....therefore any point in between will show Sirius setting within four minutes.
Here is a map, look for locations with 1st April attached:-
File:Battle of Okinawa.svg - Wikipedia, the free encyclopedia