Spread the hot rice on a tray, drizzle in the rice vinegar and toss to distribute evenly.
Leave the rice to cool, tossing often, until it reaches room temperature.
Divide the rice into eight equal portions.
Place a square sheet of cling film (larger than the nori sheet) on your work surface and position a nori sheet at the center.
Take a portion of rice and arrange in a mound at the center of the nori sheet.
Arrange strips of pickled ginger on top of the rice.
Take a chicken katsu and press lightly on the rice.
Spread tonkatu sauce on top of the chicken katsu.
Take a portion of shredded cabbage and place on top of the chicken.
Take another portion of rice and lightly press on the cabbage-topped chicken katsu.
Gather the four corners of the nori sheet and fold in to enclose the fillings.
Gather the four corners of the cling film and fold in to enclose the onigirazu.
Using the remaining ingredients, make three more chicken katsu onigirazu.
Serve the chicken katsu onigirazu right away or cut into halves to expose the fillings for a more visually appetizing look.