1-Soak the skewers: Soak bamboo skewers in water for at least 30 minutes to prevent burning.

2-Cut the chicken: Trim chicken thighs and cut into bite-sized pieces (1 to 1½ inches).

3-Make the tare sauce: Combine soy sauce, mirin, sake, and sugar in a saucepan; stir and place over medium heat.

4-Simmer the sauce: Simmer gently for 5-6 minutes, stirring occasionally, until sugar dissolves and sauce thickens slightly.

5-Add optional aromatics: If desired, stir in minced garlic and grated ginger, then remove from heat.

6-Cool the sauce: Let the sauce cool completely; it will thicken into a glossy glaze.

7-Thread the skewers: Thread chicken onto soaked skewers, leaving space between pieces for even cooking.

8-Preheat the grill: Heat a grill or grill pan to medium heat and lightly oil the grates.

9-Grill the skewers: Grill skewers for 4-6 minutes total, turning once or twice, while basting with tare sauce.

10-Finish and serve: Remove when chicken reaches 165°F and is lightly charred; serve immediately with remaining sauce.