I'm glad to see this model appear. I favor Japanese aircraft and I purchased this one from Dewayne Barrett a couple of years ago but have never built it. I would be very pleased if, when I build mine, it looks as good as yours.
I'm glad to know about the issues you discovered as you were building it.
I thought it would be easy to pin down the markings (although when the redoubtable Mike Krol and Shrike hedged on their answers, my confidence was shaken), but in fact, there seem to be some mysteries about the markings of the famous 244th Sentai, and a number of non-standard practices in the markings (not unusual for the air domination units late in the war). As you probably know, most IJAAF fighter sentais color coded their sentai tail markings, with blue
usually being used for the
hombu (headquarters) chutai.
In the earlier edition of Richard Bueschel's book on the Ki-61, there is a Richard Ward painting of a 244th Ki-61 with a blue tail. The markings are similar to yours, but there is also an orange horizontal fuselage stripe. It is identified as a headquarters chutai aircraft. That's the only such illustration I have found so far. [Richard M. Bueschel,
Kawasaki Ki.61/ki.100 Hien in Japanese Army Air Force Service,New York: Arco Publishing, 1971, Plate E]
I'm sure we'll hear more on this. And if you REALLY want to get into a complicated discussion, there is the possibly-bogus "shamrock" emblem on Lieutenant Ishikawa's (or maybe Major Kobayashi's) 244th Sentai Ki-61, which is also among the Marek 1/50 models in my (and probably your) collection. See, for example:
No.244 Hiko Sentai Aircraft, Personal Markings: CONTINUED!
Kawasaki Ki-61 "Tony": Ki-61 I Tony "Clover-leaf"
Kawasaki Ki-61 "Tony"?
WW I Connection To WW II "Shamrock" Painted On No.244 FR HIEN?
Kobayashi's Ki-61 camouflage
I look forward to seeing more of your builds, and to trying my own hand at that Ki-61 some day.
Thanks for sharing that fine model with us.
Don Boose