Cut the chicken thighs into bite-sized pieces about 1.5 inches square, trimming any excess fat as you go.

In a medium bowl, whisk together soy sauce, mirin, sake, and sugar until the sugar dissolves completely.

Place a large skillet over medium-high heat and add the vegetable oil.

Add the chicken pieces to the hot skillet without overcrowding the pan and cook undisturbed for 3-4 minutes until the bottom develops a light golden crust.

Stir and cook another 2-3 minutes until the chicken is mostly cooked through.

Push the chicken to the edges of the skillet and add the minced garlic and grated ginger to the center, stirring constantly for about 30 seconds until fragrant.

Pour the prepared sauce mixture over the chicken and stir everything together to coat evenly.

Lower the heat to medium and simmer for 4-5 minutes, stirring occasionally, until the sauce thickens slightly.

Remove the skillet from heat and stir in the white parts of the sliced green onions and the sesame oil.

Divide the warm cooked rice among serving bowls and top each portion with the glazed chicken and sauce.

Garnish generously with the reserved green onion greens and a sprinkle of toasted sesame seeds.