Speed is a weapon in air combat, I think you agree.
US planes are fast in AH (P51, F4U).
Soviet planes are fast in AH (La7, Yak9U, La5).
German planes are fast in AH (G-10, D-9, 262)
British planes are fast in AH (Typhoon, Tempest, Mosquite so-so).
Japanese planes are not fast in AH !
Italian planes are not fast in AH (well, historical reasons).
Now, IMO, Japanese planeset needs a fast plane. Ki-84 comes to mind.
So, how about Ki-84 then ?