Its also worth pointing out that IJN pilots would claim "victories" that were never intended to be classified as destroyed by them alone. Western authors post WW2 took their claims as meaning literate "confirmed kill" claims as made by western pilots.
The IJN pilots were as honest as anybody else was (maybe more) but the way that destroyed-probables-damaged were handled in the IJN/IJAAF was not the same as the LW or RAF or USAAF. Its important to know that.
"20 victories" could easily be a mix of kills, shared kills, unit kills, probables and damaged. They didnt make such a big deal about individual "confirmed" scores, they just reported what they did. They were not concerned about how other air forces tallied such things.
And yes, everybody overclaimed. Air combat was too fast paced and confusing for that not to happen. Thats just the nature of it.
As for Sakai I have also seen authors put his "confirmed kill" tally at between 20-30 with many more damaged and shared. Thats quite remarkable for a guy flying an A6M fighter and surviving the war to boot.
