"Ittou ryoudan/Ichigeki Hissatsu! Genmu Zero!"
—Zero during Genmu Zero (Ichigeki Hissatsu is unused in (U)MvC3)
Ittou Ryoudan: Genmu Zero (一刀両断・幻夢零, lit. One-Bladed Bisection: Phantasm Zero), or simply Genmu Zero/Genmurei, is Zero's Level 3 Hyper Combo. Zero gains a red aura, similiar to his "Awakened Zero" persona from his home series, and creates a massive Hadangeki that travels across the screen and does 350,000 damage. The projectile covers the entire screen and cannot be destroyed except by another Genmu Zero, making it one of Zero's best moves.
This move originally hails from Mega Man X5, similar to Zero's old Level 3 Hyper Combo from Tatsunoko vs. Capcom, Dark Hold. A notable difference in that is that Genmu Zero (originally known as Genmurei; the kanji for the number 0 is either zero or rei in Japanese) was originally a boss attack for Awakened Zero, and that Zero using it would be completely invincible as he fired two green waves at once across the screen in rapid succession. He would only use this attack after quite an amount of time would pass during the battle against him, and thus during that point X would need to spam moves with massive invincibility such as the Nova Strike in order to stay alive, as Genmurei counts as instant death. However, Zero being invincible during the attack makes it an impossible battle anyway.
In X6, the Zero Nightmare uses an alternate version known as Genmurei: Kai (Phantasm Zero: Revised), where the attack is somewhat revised for more consistent usage, and the waves appear dark gray. However, due to the Zero Nightmare's unstable and incomplete structure in comparison to the original, the attack flies around randomly, but fortunately upon contact the waves do not cause instant death and only deals a heavy amount of damage. It is also easier to avoid than its X5 version.
In Marvel vs. Capcom 3 and Infinite, where it's romanized as "Genmu Zero", Zero dons an pink/magenta/purple aura not unlike his Awakened version, and tumbles a bit in the air to slash outward a wide crescent wave that wallbounces. However, it would appear due to Zero being his normal self and not being under the effects of the Zero Virus at the time, the attack is yellow instead of green and is not truly as fatal as its X5 counterpart.
- It is highly recommended to use this move in the middle of a ground combo, cancelling his H attack to this move, if this is done the attack won't miss.
- This move has proirity against other Hyper Combos in the game, and is very devastating if used when the opponent uses their Crossover/Variable Combination, as it hits all three characters without risks if timed right.
- It is important to note that this Hyper Combo cannot hit OTG, despite its appearance.
- This is one of the few Hyper Combos to do only 1 hit.
- This Hyper Combo replaces his old Dark Hold Level 3 Hyper Combo in Tatsunoko vs. Capcom. Both abilities were oddly originally from Mega Man X5.
- Ittou Ryoudan (一刀両断) usually translates to "Cutting in two with a single stroke", which is a term for splitting someone or something into two with one strike. This references Genmu Zero's original fatal nature.
- Ichigeki Hissatsu (一撃必殺!) usually translate as "Instant Kill!", which uses a one-hit kill. However in the video game medias of Mega Man X-related games, it did not kill the opponent, just cause them a Hard Knockdown for a few seconds.