{{SpellCardTableAnime card| ja_name = {{Ruby|階|かい}}{{Ruby|級|きゅう}}{{Ruby|制|せい}}{{Ruby|度|ど}}| romaji_name = Kaikyū Seido|ja_image = ClassSystem-JP-Anime-DM.png|name image_ca = Class SystemClassSystem-OW.png|type card_type = [[Spell Card]]|property = [[Quick-Play Spell Card|Quick-Play]] [[Image:QuickPlay.png]]effect_types = Activation requirement, Effect|lore = [[Activate]] only when your opponent activates an 's [[effectMonster Card|monster]] that [[targetattack]]s your monster, and it activates its special [[destroyeffect]]s a monster on your side of the field. If the Level of your opponentthat monster's monster [[Level]] is equal to or less not higher than that of the targeted your monster's Level, [[negate the ]] that attack and effect.|number ja_lore = 相手のモンスターが自分のモンスターに攻撃、特殊効果を発動させた時に発動させてよい。そのモンスターのレベルが自分のモンスターのレベルを上回っていない場合、その攻撃および効果を無効にする。| appears_in_dm = [[Anime Only]]140, 141|sets decks = [[Anime Only]]Yami Marik|adv m/s/t = [[Anime Only]] Negates the effects of your opponent's Effect Monsters|trad attack = [[Anime Only]] Negates attacks