I ran the website in question thru Google translate. It appears to be an "imaginary" plane. (I characterize modern day surmisings of old aircraft on websites as "imaginary" and non-real aircraft concepts that first appeared printed in period publications as "fictitious").
The site lists the following specifications on this plane.
Width: 11.25m Overall length: 9.43m height: 3.65m weight: 2,688 kg Loaded weight: 4,125 kg motor: 43 Homare type takeoff output: 2,150 hp Maximum speed: 632km / h (8,500 m) Cruise speed: 450km / h practical ceiling: 11,850 m
Rate of climb: 8,000 m until 10 minutes 20 seconds Range: 1,550 km armament: 20mm × 4 Crew: 1
To me it looks a little like a Japanese version of the F8F Bearcat.