Relatively rare using the word "relatively" as compared to the thousands and thousands that had only 2x 20mm, the tens of thousand other fighters including zeros, ki44s, ki43s, every plane in the arsenal at that time, 500 was pretty small a number, and with quality problems these planes barely made enough power to take off, and if they did they would most likely break their landing gear when coming down.
There's "built" then there's "too low a quality to even bother using".... Japan was fielding a lot more of the latter in the closing days of the war, than they were of the former.