Alma Karma, also known as the "first womb", is the person responsible for the birth of the Third Exorcists.
Present day Alma is shown to be quite disfigured, presumably from his life or death fight with Yuu Kanda before the events of D.Gray-Man. He appears to be a young man with huge scars down the left side of his face and body. He has long hair, reaching his legs, and an inverted triangle over his stomach area.
As a boy, Alma was the first of the Second Generation Exorcists to awaken with Yuu second. The two were forced numerous times to try and bond with Innocence, with each attempt tearing them to pieces. They would survive thanks to their regeneration abilities. Alma greets all of the unawakened exorcists as part of a daily routine.
Later when Alma hears that Yuu will put to sleep, he knocks out Yuu's attendants and carries Yuu away, not wanting to lose his only "friend" whom he'd just gained. However as they enter a sewer system, they are caught by Crow. Crow uses talismans to stop the two but before they can be fully activated, Alma kicks Yuu over the edge down into the canal telling him "if (he's) lucky (he) might get outside," before Crow knocks him out.
When Yuu was recaptured, Alma tore out of his restraints and attempted to save Yuu, eventually falling down a shaft into a room where several corpse cocoons were kept. When Crow caught up and attacked, he somehow grew a blade from his right arm and killed them, slicing open the cocoons in the process and revealing the bodies of other "Second Exorcists." After Road (who, with Allen, and was not part of the world of memory) explained the truth of the project, Alma was seen at the end of the chapter with tears (perhaps of anger) in his eyes.
Alma killed the previous Asian Branch Sixth Institute after learning the truth of the Second Exorcist program. When Yuu saw the massacre, Alma stabbed him and asked him to join him in death, hoping to end their misery as "Second Exorcists" and have the Black Order learn their mistake of using them as tools. Yuu learns that Alma committed the murders in order to protect the person he loved. However, Yuu then stood up and slashed Alma in half with his own bonded Innocence, as Yuu desired to live to see that person once more, even if it means killing his best friend.
After the Noah Family invaded the American branch headquarters, Cyril Kamelot used his powers to move the body of Alma Karma, having him attack Allen Walker. After that, Alma and Yuu Kanda's history was revealed by Wisely via his Demon Eye to Allen and Road Kamelot.
Alma Karma is awakened after Allen Walker, Road and Yuu Kanda break out of Wisely's Demon Eye powers. Alma is seen to be inside a huge entity that attacks everyone. The large entity then drops Alma Karma and he is seen to return back into the Headquarters in his new form. Unlike the other 3rd Exorcists, Alma Karma has the form of an Akuma, resembling a Level 4, with what seems to be an armoured outer shell and pattern/symbols on his body in a similar style. He has a disk, instead of a halo, floating upon his head.
Alma has the power to make any part of his body into a weapon. These weapons are laced with innocence which makes his entire body an anti-akuma weapon. It is currently unknown if this is a type of parasitic Innocence or something else entirely. Alma can not completely control his powers because of his unstable personality.
Later, with his cursed eye, Allen finds out that Alma's soul is the soul of the woman whom Kanda Yuu has sworn to find. Before Alma dies, Allen uses the Ark to transport Kanda and Alma to Mater city (the place Allen and Kanda fought together the 1st time) to allow them to be together. Alma eventually dies in Kanda's arms.