Just commenting with updated info for readers: The vegan plate set has been discontinued. Currently (as of December 2024), there is the option to change the patty on several of their regular menu Hamburg items to a zeromeat patty, but this does not guarantee they are vegan. The "Japanese-style Hamburg steak" still lists chicken as an allergen in the zeromeat version. The "Hamburger Steak with Grated Daikon Radish Sauce" does not list any animal allergens in the zeromeat version, but not all animal ingredients are considered allergens. Katsuo (bonito fish) is very common in Japanese sauces but isn't considered an allergen so would not be listed. So there's a possibility that the soy sauce on this hamburg may contain katsuo.