This is honestly one of my favorite dishes…ever.  My brother taught me how to make this after coming home from living in Japan for two years and was very specific about several items.
1.  You lay the chicken on top of the rice and drizzle the sauce over the chicken.  If it falls on the rice that’s okay, but it is not okay to directly/intentionally put the sauce on the rice.  (Mr. Jiggs makes fun of this all the time.)
2.  The rice must be sticky rice and leftover rice must be wrapped in plastic wrap and frozen until you need it.  Preferably, you make them into 1 serving packets to cut down on how long you have to re-heat them.
3.  Deep fry the chicken in oil that just barely crackles when you flick a small amount of water onto the oil.  That will cook it through the quickest without over browning it or letting it absorb too much of the fatty oil. 
Okay, that last one is not a rule, but part of the directions for making the tonkatsu.  But I’ve abandoned that method of cooking the tonakatsu in favor of baking it because it cuts out fat and labor.  Deep frying the tonkatsu can take a long time if you’re making a lot and requires you to stay at the stove watching the chicken to make sure it doesn’t burn.  Baking it lets you make a lot at one time and walk away to break up the current argument between the Piggs.  
I can easily imagine my brother teasing me about the change in cooking methods not being authentic. 
I don’t care.  It still tastes wonderful.
One thing I will not change is the sauce.  It’s Bulldog brand Tonkatsu Sauce (Vegetable and Fruit Sauce) and it is SO good!  I usually get mine at an Asian market in Arizona, but you can buy it on Amazon too.  I just ran out so I might try that method now that I live far from that Market.
So here’s the recipe.  Well directions because the amounts aren’t all that specific.  Go with it…it makes you feel like a professional cook!  🙂
Tonkatsu

Chicken tenders (or other kind of meat)
eggs
panko (japanses style bread crumbs)
flour
tonkatsu sauce
oil

Heat a large amount of oil (enough to submerge the chicken pieces) in a sauce pan until it barely crackles when you flick a small amount of water in it. Place the flour, eggs, and panko in three separate shallow bowls.  Beat the eggs slightly.  Coat the chicken in flour, then dip in the beaten eggs, and roll to cover in the panko.  Deep fry the chicken in the oil until golden brown or cooked through.  (I usually have to cut mine open to be certain)  Serve over sticky rice with tonkatsu sauce drizzled over the chicken.

To bake instead of deep frying,  lay the chicken on a baking sheet and bake at 350 for approximately 15 minutes.