After cooking the sushi rice, mix it with ½ a teaspoon of salt and 2 tablespoons of furikake (I actually sprinkled the furikake on the onigiri after shaping them, but in hindsight, I think it's better to add directly to the rice).
Cut the chicken meat into small pieces. Transfer to a bowl with the rest of the marinade ingredients. Mix until combined, then refrigerate for 30 minutes.
In a small bowl, combine the teriyaki sauce ingredients.
Heat 1 tablespoon of oil in a large nonstick pan over medium-high heat. Add the marinated chicken and cook for 2-3 minutes until cooked through.
Reduce the heat to medium. Add the garlic and cook for 30 seconds. Add the sauce mixture and continue cooking until the sauce thickens into a glaze. Remove from the heat.
To wrap the onigiri, wet your hands with water then scoop ⅓ cup of rice into your palm. Make a small well in the center and fill it with 1 tablespoon of filling. Scoop another ⅓ cup of filling to cover the filling then use your hands to shape into a triangle. Wrap with a strip of nori.