Working on a LS model of a KI-46 Dinah II. My research indicated that this aircraft was often found in a hard demarcation between colors. It was also found in soft edge though, at least that is what I've found.
If you look at the box art of Hasegawa's 1/72 scale, (the proper scale Ha Ha) Dinah II it appears to be soft edged as well. Although the accuracy of box art is sometimes in question I am told. Thanks for the input. Russell

It may have been when the painting at the factory occurred. A hard line when all was quiet...a soft edge when B-29s were raining down destruction and one had to hurry.