Dove;
Classic Teriyaki just has those three ingredients. Like everything else, however, each cook puts their own spin on it. My best friend uses soy sauce, ginger, garlic, honey and beer! Still mighty tasty!
you need to thin out the soy sauce or it will make your food too salty, depending on how long you marinate it for. if it's a long soak, then use equal parts of soy sauce and mirin or simple syrup.