Zanpakutō Name: Mugetsu
(無月, Moonless Sky) Zanpakutō Element: Shadows, Deception, Mist, Distortion.
Shikai Release Command: Shatter and Disperse, Mugetsu! 
Once the release is complete,
Mugetsu shatters and disperses into 666 playing cards, these cards float around Yuu and are surrounded by a glow that resembles blue flames. The cards are know as Phantom Cards and these cards in this state are completely harmless, in fact they are impermeable to all objects. The cards can only be touched by Yuu himself. Once Yuu grabs a single card and shatters it with the palm of his hand, the Phantom of Darkness begins.
Phantom Darkness (ファントムダークネス)
This phenomena occurs when Yuu shatters a single Phantom Card, this acts as a trigger for the Phantom Darkness. Once a single card is shattered, all 666 cards begin to glow brightly and burn in Blue flames, then from it the flames becomes a thick blue miasma, spreading out from the cards. The miasma surrounds the whole battle field instantly giving off the effect that the miasma runs forever. This effect is a result from one's sense being dulled to the point where even though there is an exit, one cannot see it or decipher it's location to be able to escape. The miasma gives off the effect that the miasma runs on forever and as such one can not simply escape the miasma. The only way to escape the miasma is to defeat the controller of
Mugetsu or if Yuu himself dispells the ability.
The Miasma itself also serves another purpose, it can under the order/will of Yuu to quickly come together and form a solid object, the only rule is that the object formed has to be a materialistic object and also cannot form on the presence of another being. The object formed is essentially a concentration of Reiatsu. However, because of it's nature the appearance of the object formed is something of what Yuu wishes. The solid object formed is also flawless in it's complexity and design, meaning that the object formed will exert exactly the same properties as if the real object would.
The Miasma is formed from Yuu's Reiatsu. Releasing the Miasma however does not drain any of Yuu's Reiatsu. The Miasma once released can lay dormant in any physical object (besides the opponent and his/her Zanpakutō) and continue to lay there unless called upon. The Miasma once dormant is undetectable.
Bankai Release Command: Bankai! Labyrinth of Nightmare (悪夢の迷宮)
In it's Bankai state,
Mugetsu retains all of it's powers whilst in Shikai state, that is the Miasma stays. In addition to it's original powers, the two combatants are also transported into the world known as
The Labyrinth of Nightmare. The Labyrinth of Nightmare is a never ending forest shrouded in a constant miasma that can not be dispersed under any conditions. The only way out is for
Mugetsu to be deactivated or for Yuu to be defeated, one of these two things will deactivate
the Labyrinth of Nightmare.
Order of Chaos (オーダー・オブ・カオス)
The Miasma causes six nearly identical clones to materialize. Each controlled by Yuu directly through thought. Each clone’s eyes takes up a different colour to one another. Each clone possess an unsealed version of
Mugetsu. The clones are bounded by a spirit link to both Yuu and his opponent and are virtually perfect clones, they can cast kido and exert any special abilities as the original Yuu would. When one of the clones is destroyed or makes contact with any part of the opponent, one of the opponent's sense is stopped and void until Yuu is defeated. When all 5 clones under Yuu control makes contact or is destroyed, all five senses are stopped. The colors of the eyes correspond to the sense that is distorted. These colours and sense relation will be assigned prior to battle and are random every battle.