Rice ball is called "Onigiri" in Japanese. Mostly it's shape is triangle and you can either mix ingredients into rice or fill your favorite ingredient in the rice ball, or both!
There are many furikake (rice seasoning) products at Asian grocery stores, so try out and see how you like it done :D
--------------------------------- Onigiri
Difficulty: Very Easy Time: 3min Number of servings: 2
Ingredients (2 rice balls) 160g (5.7oz.) cooked white Japanese rice Furikake (rice seasoning) or filling of your choice
How to Use Furikake: 1. Place cooked rice in a bowl. 2. Mix Furikake of your choice according to the amount written on its package. 3. Wet your hands with water so that the rice won't stick. 4. Place the seasoned rice on your hand. 5. Form the rice into a triangle, round, or cylinder by pressing lightly with your palms.
How to Use Filling: 1. Place cooked rice in a bowl. 2. Wet your hands with water so that the rice won't stick. 3. Place the rice on your hand. 4. Make a hole in the center of the rice and place the filling. 5. Form the rice into a triangle, round, or cylinder by pressing lightly with your palms.
You can wrap your Onigiri with a strip or a sheet of Nori seaweed if you prefer.