Monster Zone

Monster Zone
Japanese	モンスターゾーン (formerly モンスターカードゾーン)
Japanese (romanized)	Monsutāzōn (formerly Monsutākādozōn)
Japanese (translated)	Monster Zone (formerly Monster Card Zone)
English	Monster Zone (formerly Monster Card Zone)
Other names French: Zone Carte Monstre German: Monsterkartenzone Italian: Zona Carte Mostro Korean: 몬스터 존 Monseuteo Jon (formerly 몬스터 카드 존 Monseuteo Kadeu Jon) Spanish: Zona de Cartas de Monstruos Traditional Chinese: 怪獸區 Guàishòuqū (formerly also 怪獸卡牌區 Guàishòukǎ Páiqū)

Monster Zones (モンスターゾーン Monsutāzōn), formerly Monster Card Zones (モンスターカードゾーン Monsutākādozōn), are the 5 Boxes with "2" on them, in this picture. You can only have in play, at any one time, 5 Monster Cards and/or Monster Tokens. If all 5 Monster Zones are occupied, then you cannot Summon another monster, unless you Tribute one or more of them first or use them for a Fusion/Ritual/Synchro/Xyz Summon.

Some cards, such as "Ojama King", "Ojama Knight", and "Ground Collapse" affect the number of Monster Zones that are usable.