Place chicken in a glass dish. Remove excess fat from chicken breasts. Combine sake, oil, sesame oil, ginger, garlic, and soy sauce in a small bowl. Pour mixture of chicken, cover and refrigerate for 15 minutes. Preheat grill for medium-high heat. Place chicken on a well oiled grill grate, making sure to reserve marinade. Baste with reserved marinade and cook for 6 minutes. Turn chicken, baste, and allow to cook for another 6 minutes. When juices run clear, remove chicken from grill and serve.