Grilled miso chicken

Ingredients:

• 2 tablespoons light soy sauce (usukuchi shoyu)
• 2 tablespoons sake
• 2 tablespoons mirin
• 2 tablespoons light miso
• 2 green onions, crushed and slivered
• 1 teaspoon minced ginger root
• 1 garlic clove, minced
• 8 boned chicken thighs, skin intact
• 1 tablespoon seven-spice powder (optional)