Appetizers are small companions that are always attatched to the mochidogs. Appetizers can be applied to any rarity MYO mochi but if your mochi is premade without one the only way to get one is with the companion potion available at Starr's potion shop for only a small amount of dangoCoins. However, if your mochi has an appetizer and you don't want it anymore it can be removed for free.