1/4 cup reduced-sodium soy sauce
1/4 cup mirin
1/4 cup sake
1 Tbsp sugar
Japanese seven-spice powder
4 skinless, boneless chicken breasts, cut lengthwise into 12 strips
12 bamboo skewers, soaked in water for at least one hour
Stir together the soy sauce, mirin, sake and sugar in a nonreactive bowl. Add the chicken strips and marinate for at least 2 hours, and up to 8 hours.
Preheat the broiler and line a baking sheet with aluminum foil to catch the drips (and make clean-up easier). Thread each strip of chicken onto a skewer, and place on the baking sheet. Brush with the marinade. Cook for 5 minutes, then remove from the oven and turn the skewers. Baste again with the marinade. Cook for an additional 3-4 minutes. Brush one more time with marinade, cook for 1 minute, and remove from the oven. While the chicken is warm, sprinkle with Japanese seven-spice powder.
Serve warm or at room temperature.