Place the cubed chicken thighs in a bowl and combine with the dark soy sauce, light soy sauce, sesame oil, sugar, rice vinegar, garlic, and ginger. Mix well and marinate for at least 15 minutes, or ideally 1 hour.
Heat a pan over medium heat with a bit of oil. Add the marinated chicken along with the marinade and cook for about 8 minutes, flipping halfway through and stirring slightly, until the chicken is cooked through and the sauce has reduced into a glaze.
Remove from the heat and serve over a fresh bowl of rice.
Optionally garnish with kewpie mayo, soy glaze, furikake, scallions, and peppers.
