Stig,
If you use the AAIR accident database (
http://92.53.241.206/dbSearchAF55.asp) and look for (e.g.) P-51 for type and JPN for country, you'll get a good idea what Squadrons and/or Groups were based in that country around 1948. At first glance there were 35th FG (Johnson AB), 8th FG (Ashiya), 425th and 475th FG (Itazuke) and some more...
Regards,
Leendert