Yup
Imperial Japanese Army
and
Imperial Japanese Navy
Like the US, the Japanese had an almost entirely separate list of aircraft for the Army and Navy. Because of that it is relevant to refer to US aircraft as USAAF or USN and Japanese aircraft as IJA and IJN.
If the aircraft is a "Ki" it is an Army aircraft, Ki-61-I-Otsu for example means:
Ki = airplane
61 = Sixty-First airplane in the IJA
I = Version one
Otsu = Modified
In other words the Ki-61-I-Otsu would be a lightly modified version of the Ki-61-I-Ko
The IJN used a different naming scheme. For example the A6M5b:
A = Carrier fighter
6 = Sixth carrier fighter to enter service in the IJN
M = Designed by Mitsubishi
5 = Fifth major version
b = Third minor version of the major version
The D3A1 is:
D = Dive bomber
3 = Third dive bomber to enter service in the IJN
A = Designed by Aichi
1 = First major version
The N1K2-J is:
N = Float plane fighter
1 = First float plane fighter to enter service in the IJN
K = Designed by Kawanishi
2 = Second major version
-J = Modified to be a land based interceptor
The J2M3 is:
J = Land based interceptor
2 = Second land based interceptor to enter service in the IJN
M = Designed by Mitsubishi
3 = Third major version
