Cut the chicken into bite size pieces. In a medium bowl, add the chicken, soy sauce, sake, salt, sugar, black pepper, grated ginger, and garlic. Mix to coat the chicken and marinate for 30 minutes.
Mix the flour and corn starch, and coat the chicken pieces with the flour mixture.
Heat oil at medium high heat (350F). Deep-fry the chicken for 5 to 6 minutes or until cooked through.