This version of the Ki-84 is the Late 1943 / Early 1944 version…
Powered by the 1800 horsepower Ha-45-11 engine.
The BR V Ki-84 is the late 1944 version with 2000 horsepower Ha-45-21 engine.
So what im thinking is…
Ki-84 early (1800hp) with 2x 100kg bombs would be BR IV
Ki-84 late (2000hp) with 2x 250kg bombs would be BR V