A late-comer's 4 cents worth (tuppence at the current exchange rate with rounding) ...
As an earlier post pointed out, a comparison of the Règia Aeronautica against the Japanese should not be limited to "aircraft performance" and fighter performance at that.
Today, we talk about the importance of "command, control, communications, intelligence, surveillance and reconnaisance". That's because these "force multipliers" are critical to "winning" the whole shooting match.
The edge here has to go to the Japanese forces. Both the JAAF and JNAF placed great importance on recon planes that can fly high and fast with radio links to headquarters and even bombers in the air. The fore-runners to the Ki-16 "Dinah" or D4Y "Judy" of WWII were Ki-15 / C5M used in the Sino-Japanese War. Both the JAAF and JNAF developed some very effective tactics using this ISR capability.
During the air campaign against the Chinese in the distant Szechuan Province, pairs of these high-flying aircraft would go ahead of bomber formations and report back on the weather as well as the status of the opposition. The long range of the Japanese bombers allowed them some very interesting options. Typically, Chinese interceptors would be scrambled in response to their air raid warning net reports of incoming raids. With almost "real time" surveillance provided by the recon planes, the bombers sometimes used their great endurance to circle and wait until the Chinese fighters had to land to refuel. At that point, they would try and catch the Chinese fighters on the ground. After getting caught a couple of times, the Chinese had to develop tactics to counter this ploy. (The Ki-15 / C5M flew high and were very elusive, the Chinese were not able to intercept them on a consistent basis.)
The aerial recon is only one component, the JAAF and JNAF routinely used intelligence from many different sources. These include special forces equipped with radio, SIGINT using radio intercept ... In a putative conflict against Italy, the Japanese would have an edge for the simple fact that they probably had more people trained to understand European languages than Italians have people understanding Japanese! (The Chinese were a better match - plus they had talented crypto-analysts that broke the JNAF tactical codes used during this period.)
This may go some way towards explaining why so many Allied aircraft were caught on the ground by the Japanese during the early days of WWII. Japanese bombing accuracy, particularly that of the JNAF, was excellent. Early in the war, JNAF divebombers consistently scored a higher rate of hits than their USN counterparts on radically maneuvring targets. They picked the best people and trained them very hard ... developing some excellent techniques and very sound tactics.
Oh, did we forget the fighters? They were pretty good too, as some RAF veterans of the ETO and MTO found to their cost when they faced JAAF and JNAF fighters for the first time. Trying to fight the more agile Japanese fighters the same way they fought in Europe or North Africa was definitely not "habit forming".
Ever wonder why the Japanese were able to achieve success using two puny synchronized rifle-caliber machine guns in their fighters?
Training!
Good instructions and practice, lots of it. During the early part of WWII, only the USN could match the Japanese (due to a good pre-war training program). Gunnery training, particularly air-to-air, was sadly deficient in the USAAC. The same applied to many European air forces with the exception of the Luftwaffe.
The Allies eventually caught up with good systematic "Operations Research" and development of better training as well as new equipment such as the gyro "lead computing" gun sights (Ferranti GGS, K-14, Mk 18 ). However, the Italians did not appear to have the benefit of similar organized R&D efforts.
Certainly, every force had their "virtuosi" who made a great impact. However, it takes good planning, organization and training in a large scale to achieve the level of combat readiness and effectiveness of the early war JAAF and JNAF. I think that gives Japanese a significant edge over the Règia Aeronautica.
It took the U.S. a great deal of effort to overcome this early edge in the Pacific. This effort was clearly something that the Italians were unable to duplicate during WWII in the scale that was needed ... Without this support, even the undoubted talent and courage of Italian pilots would likely not be enough to prevail against the better prepared Japanese forces.