Marinate the chicken breast in a mixture of sake, soy sauce, and mirin or maple syrup. Let it sit for at least 20–30 minutes, or longer if possible, so the flavors fully infuse the meat. Heat a pan or grill and cook the chicken until golden on both sides and fully cooked through. Slice the cooked chicken, sprinkle with fresh parsley, and serve with a fermented pickle on the side.