Isn't it just easy to remove the clutch basket by putting the first gear on and then same time press down the rear brake lever with your leg and open the locking nut?
That way I opened and installed the locking nut in Honda CX500 when I installed the clutch basket to the right torque.
Rear brake prevents the rear wheel turning and because the gear is on the cardan axle prevents engine turning.
No extra special tool needed. Or is kawa engine somehow different and that method does not work?