Begin by rinsing the sushi rice under cold water until the water runs clear, then drain. Cook the rice with 1.5 cups of water in a rice cooker or saucepan over medium heat.

While the rice is cooling, cut the boneless skinless chicken into small pieces. In a bowl, combine soy sauce, sake, and baking soda. Add chicken pieces and toss well to coat.

In a small bowl, whisk together soy sauce, mirin, brown sugar, and cornstarch to create the teriyaki sauce.

Heat oil in a nonstick pan over medium-high heat. Add the marinated chicken pieces and cook for about 2-3 minutes, stirring frequently, until the chicken is cooked through and golden brown.

Lower the heat and add minced garlic to the pan. Sauté for about 30 seconds, then stir in the prepared teriyaki sauce and cook until it thickens.

To form the Chicken Onigiri, wet your hands and scoop about ⅓ cup of the prepared sushi rice into your palm. Create a well, place a tablespoon of chicken filling, and cover with more rice. Press gently to shape into a triangle.

Cut nori sheets into strips or squares and wrap around the base of each rice triangle.