The Extra Deck Zone (Box 4) (エクストラデッキゾーン, Ekusutoradekkizōn; previously Fusion Deck Zone, 融合デッキゾーン, Yūgō Dekki Zōn), is where your Extra Deck (previously called Fusion Deck) resides face-down at all times. It is usually colour-coded gray (purple when it was called the Fusion Deck Zone), and resides next to the spell and trap card zone and at the bottom-left of your field, below your Field Card Zone.