2Place chicken, skin side down, in a cold large cast-iron skillet and cook over medium heat, undisturbed, until chicken skin releases easily, about 5 minutes. Reduce heat to medium-low and continue to cook, lifting up once or twice to let hot fat run underneath, until skin is evenly golden brown and crisp, about 12 minutes.
3Meanwhile, whisk soy sauce, mirin, and sake in a small bowl.