Pierce the chicken breast with a fork so the seasoning absorbs evenly. Coat the chicken with sake, sugar, garlic powder, and salt. Cover loosely and microwave until fully cooked for about 3-4 minutes. Let it cool in the fridge, then slice.
Combine water, chicken stock powder, salt, soy sauce, lemon juice, and sesame oil in a bowl. Stir until fully dissolved, then chill.
Cook somen noodles according to package instructions. Rinse under cold water and drain well.
Place noodles in a bowl, top with sliced chicken, lemon slices, and daikon sprouts. Pour over the chilled broth and serve.
