So after I had watched this video a few times, I gathered up my ingredients and started cooking. I chopping up the vegetables, and since I didn't have normal chicken breasts, I actually used frozen already cooked grilled chicken pieces. You know, the stuff you find in the frozen food section for frozen dinners. So I heated the chicken up in the microwave before I added them to the pan. Aside from that, I didn't add the mushroom, but I did add chopped bell peppers for my omurice. I also didn't use as much ketchup, since Japanese ketchup is slightly different from American ketchup.
I definitely feel like this is a recipe you can play around with. I do suggest keeping the ketchup in the recipe, it actually tastes really good. This is an easy recipe and very delicious, so go on and give it a try ^_^.