While at the Xavier Institute, Armor and Wing were attacked by Ord of Breakworld. Armor used her mutant powers to punch Ord, taking him by surprise. Following a brief scrimmage, Armor and Wing were overpowered by Ord, and Wing was injected with the Hope Serum. Depressed by the loss of his powers, he committed suicide in the Danger Room. After Wing's death, Armor, Kitty Pryde and other Xavier students found themselves trapped in a sentient and hostile Danger Room. Danger eventually fled the Institute.
Armor was with the X-Men when they were abducted to Breakworld by S.W.O.R.D. because Breakworld had develop a weapon capable of destroying the Earth.
Ord alerted Breakworld's ruler to the arrival of the X-Men, and they sent a fleet to attack their ship. S.W.O.R.D.'s ship was heavily damaged after the attack, and the X-Men were separated. Armor ended up with Wolverine, who inducted her into the X-Men. Armor was given one of Kitty Pryde's uniforms. Armor aided the X-Men in liberating Breakworld and saving Earth.
M-Day and Messiah Complex
In the wake of M-Day, only 27 students (including Armor) retained their mutant powers. Along with most of the other powered students, Armor participated in Emma Frost's battle royale to become a member of the New X-Men.
Armor briefly joined the New X-Men when Surge assembled the team against the Purifiers. At the Purifiers' headquarters, they discovered that Rictor, of X-Factor there, and that the Purifiers didn't have the Messiah baby. Preparing to leave, the group was attacked by Lady Deathstrike, who mortally wounded Hellion. Pixie teleported the group, but they were spread out between the Mansion and Washington. Armor was brought back to the mansion by Iceman with the other New X-Men. When a Predator X showed up at the mansion, Armor teamed up with Gentle and battled it in the infirmary. Pixie, believing X-23 could defeat the monster, teleported it and the entire team, along with Armor, to the battle between the Marauders and the X-Teams taking place on Muir Island.
Once Danger joined the X-Men on Utopia, Armor confronted her in the X-Brig about her part in Wing's death. They battled, until Danger disclosed that she sees Wing inside her program everyday, and that she is trying to learn about mutants. Armor realizes that Danger feels guilty about what happened to Wing, and agrees to teach her about mutants, starting with Wing.
While training with Wolverine, Armor's exoskeleton enlarge to mammoth-size. Shortly after, she was informed her mother and brother had died. Accompanied by Cyclops, Emma Frost and Wolverine, she returned to Japan to attend their funeral and reconnect with her distance father.
Armor is a mutant with powers based around a psionic exoskeleton, including:
Psionic Exoskeleton-Armor: Armor can generate an enormously strong, powerful, durable and impenetrable psionic exoskeleton armor around her entire physical body by drawing more power, energy and strength from the bloodline of her Japanese ancestors. This exoskeleton drastically enhances her strength, endurance, stamina, agility, invulnerability and durability, though she can only maintain it for short periods of time lest the effort leave her drained. In situations of extreme emotional stress, Armor can significantly enhance her exoskeleton's size, strength, agility, dexterity, and durability, but she can only do so briefly as the strain can render her unconscious. The strength, power and size of her psionic armor greatly enhances and increases tremendously when her relatives die. In addition, the body armor greatly heightens and strengthens the concussive force behind her offensive and incredibly destructive blows and makes her practically invulnerable and immune from a significant degree of physical harm and damage. To some extent, she can shape her armor, such as her ability to form Wolverine-like claws and make them extend outward.
Superhuman Strength: Her "armor" greatly strengthens and amplifies the concussive force behind her unusually offensive and highly destructive blows. Her psionic armor grants her enough superhuman strength to lift a Skrull ground tank and punch someone through several walls of a building and even assisted Colossus in restraining a small ship capable of breaking orbit from lifting off.
Superhuman Durability/Invulnerability: The body armor is depicted as enveloping her completely and protects her from tremendously strong and powerful attacks and in some depictions, Armor's armor is strong and durable enough to survive the heat caused from a long fall through the atmosphere. Likewise, she is able to fully withstand the impact from falling to the ground from high up in the atmosphere without any physical or external injury.
Concussive Blast: She can cause her armor to release a large solid, concussive blast of energy, but it takes lot of concentration.
Armor has received combat training from Wolverine and classes in tactics from Cyclops.
Armor speaks Japanese.
Armor's psionic-energy exoskeleton armor is vulnerable to lasers as "it has to let light in," and Adamantium due to its unique and special abilities and properties, such as Wolverine's claws, although he is not able to go through it with the rest of his body. In this case, she only remained uninjured because the distance between her armor's perimeter and her body was slightly greater than the length of Wolverine's claws.
Cost Of Power: Armor's powers increase when a member of her family dies.
With Shadowcat's departure/sacrifice in the Breakworld, Armor officially took her place in the roster of Astonishing X-Men.
Armor later confronted Danger to get revenge for Wing's death; however, Danger revealed that despite being a mechanical entity and having repeatedly deleted and adjusted her memory banks, she still cannot erase the guilt she feels from the incident. This appeased Armor.
Armor's body armor is initially partially explained as being somehow composed of something related to her family lineage and ancestors. It is later described as being composed of memory. This is stated in an issue of Wolverine: Origins, when Armor's armor is able to withstand blows from the Muramasa blade, which can cut through any material, since memory is "the only material that the blade cannot cut through." Similarly, in Astonishing X-Men, vol. 3 #39, Armor's armor expands and grows to the size of a building due to the fact she feels strongly about not attending her recently deceased mother and brother's wake.