Arborio Rice (or any short grain rice)
Left over meat or filling of your choice
Sesame Seeds
chopped green onions
soy sauce.

So while my family was visiting, my mom and I made these. She got the idea from my cousin Heather. While we didn't do them perfect, they were still good. Essentially they are just a very sticky rice that has been hand shapped into rice balls with some filling in them.
To get the rice sticky, I used arborio rice in the rice cooker with a lot of water. Pretty much 2:1.
For the filling we had some left over roast that we braised for the day until it fell apart. (We did end up over cooking them, but that wasn't part of the recipe). Any left overs or pre cooked filling could be used. Chopped chicken? Spam? Sauteed Onions? Chopped Nuts? Chocolate?

Once the rice has cooked and cooled enough to touch, you'll want to wet your hand, grab a small handful of rice. Flatten the rice out to be pretty then, but not breaking apart. Add some filling, wet your hands, grab a little more rice, and put on top. Shape it into a ball and get the edges to stick to be whole.  Let sit until cool, about 15 minutes.

We then roasted some sesame seeds, and rolled the balls in those before topping with some green onions and drizzled on some soy sauce.

Other variations have you wrapped them in seaweed. That would be tastey as well. This recipe is similar to Musubi, which my roommate Sarah likes to make.