[ojcar]

In fact, historically it's not so very important. The high altitude B-29 raids proved to be so inefective over Japan (because the jet stream), that USAAF turned to medium and low altitude raids. At this altitudes, the Shoki were fully capable (and the IL-2 sky much nicer).

Saburo, look for these books (emule is your friend):
-B-29 hunters of the JAAF (Osprey).
-Profile Aircraft 255. Nakajima Ki-44 Shoki (Tojo)
-Aircam Aviation series n