If you control a "Ninja" card or a face-down Defense Position monster: You can Special Summon this card from your hand. When your opponent activates a monster effect (Quick Effect): You can target 1 face-down Defense Position monster you control; change it to face-up Defense Position, and if you do, change this card to face-down Defense Position, then, if the targeted monster was a "Ninja" monster, except "Mitsu the Insect Ninja", negate that opponent's activated effect. You can only use each effect of "Mitsu the Insect Ninja" once per turn.