Zantetsuken

Zantetsuken (ザンテツケン) is an ability which appears in Kingdom Hearts Final Mix, Kingdom Hearts: Chain of Memories, and Kingdom Hearts II Final Mix. It consists of holding the Keyblade tip-backwards, then performing a single powerful slash through the opponent's body so quickly that the cut doesn't appear until after the technique is finished. It is usually a ground combo finisher, and can defeat minor enemies in a single hit. In Kingdom Hearts Final Mix it requires 2 AP to equip, while in Kingdom Hearts II Final Mix it is only available while using Limit Form. In Kingdom Hearts: Chain of Memories, the damage it inflicts is sharply reduced, and instead it is able to break the opponent's card and render it unreloadable.

Kingdom Hearts Final Mix

 * Sora learns "Zantetsuken" after defeating the Kurt Zisa.

Kingdom Hearts: Chain of Memories

 * Sora learns "Zantetsuken" starting at level 22.

Kingdom Hearts Re:Chain of Memories

 * Sora learns "Zantetsuken" starting at level 27.

Kingdom Hearts II Final Mix

 * Limit Form has "Zantetsuken" as a default ability.

Kingdom Hearts 358/2 Days
While wielding the Oathkeeper, Two Become One, or Dream Sword, the ground combo finisher is a Zantetsuken-like slash.

Etymology
In the Final Fantasy series, "Zantetsuken" (斬鉄剣) is the signature technique of the summon Odin. It typically inflicts Instant Death upon all enemies.

Trivia
In Kingdom Hearts Final Mix, Zantetsuken is able to completely stun Unknown, and doing so rewards Sora with 100 Tech Points.