All of the members are criminals as they have betrayed their village of origin and banded together for the ultimate purpose of world domination. Akatsuki is initially introduced midway into the first part of the series, though does not begin acting as a major antagonist until the start of the second part.

The name arrancar is a Spanish verb meaning "to remove" or "to rip off," a reference to an arrancar's removal of its hollow mask. In the manga, arrancar is written using a kanji spelling meaning torn mask (破面 yamen?), but is pronounced as the Spanish arrancar (アランカル arankaru?).

at any given point in time, is composed of no more than ten primary members. There is no known criterion required for joining the organization, though all known members have severed all ties with the village they grew up in and are S-class criminals, the most wanted and dangerous individuals in the series.
Two members, Itachi Uchiha and Sasori are known to have undertaken a challenging task around the time of their joining the organization: Itachi killed almost all the members of his family in a single night, though it is unclear what his true reasons for doing this were. Sasori, during the course of the battle in which he eventually meets his demise, comments that "[he] hadn't had this much difficulty since joining Akatsuki". In Deidara's case, however, he was forcibly recruited by other Akatsuki members as a result of his effective work as a terrorist.
Members of Akatsuki work in teams of two. Teams are built to complement each other's abilities and talents to create a formidable duo. For example, Kakuzu uses Hidan's immortality to his advantage by using large-scale attacks on those Hidan has pinned down; being immortal, Hidan survives what is normally fatal to his opponent. Zetsu is an exception to this, as he operates by himself at all times. Members whose partners have died also operate by themselves until a replacement can be found. At the very least, members maintain a functioning working relationship with their partner, with some form of loyalty to one another being present in most cases. In other instances a member will only work with their teammate so long as it furthers Akatsuki's goals, with all other matters being a source of dispute between the two. In general, Akatsuki members are unconcerned with the fate of their other comrades, their only point of interest concerning someone's death being who was strong enough to kill them.
Akatsuki is a widespread organization, with its members constantly traveling between countries and its agents operating out of various villages throughout the world. These agents work for specific members for varying purposes; Sasori has a number of agents under a form of mind control that he uses as spies, while Kakuzu has a group of people that take care of his finances. Because the various members are often so far apart, making a meeting in person impractical, they can communicate through a form of telepathy. If there is a need for the group to have more of an interaction with each other, members can use a form of astral projection to meet at one of Akatsuki's many secret lairs. When their entire group meets like this at the end of the first part of the series, one member notes that it had been seven years since they had all been together in such a fashion. Their meetings are much more frequent in the second part of the series due to their increased activity.

and even if they manage it the change is not significantSōsuke Aizen is able to artificially create arrancar with the Orb of Distortion, which also unlocks much more of their potential than a natural transformation would. The process of turning a hollow into an arrancar is called shinigamification.
Arrancar and ordinary hollows differ in two ways: the location of their holes and the near-total disappearance of their masks. When hollows become arrancar, the chances of them retaining a humanoid form increase with their intelligence; only vasto lorde-class arrancar will definitely assume a humanoid form. If powerful enough, an arrancar can seal his or her excess power into the form of azanpakutō. Unlike with shinigami, this zanpakutō is simply the hollow's true form sealed into a sword. Therefore, an arrancar's release of their zanpakutō is merely a temporary restoration of their former selves. An arrancar release is called resurrección. Arrancar do not have a known second release.

All members also wear nail polish of varying colors on their fingernails and toenails. When starting a mission they wear large conical straw hats with small spike-like bells hanging from them to block their faces, but the hats are discarded once they have been discovered. In addition to this more standard wardrobe, members continue to wear forehead protectors from their former home villages, but scratch a line across their village's symbol. This is done to indicate that their ties to the village have been severed and they no longer give allegiance to their former homes. Not all members have their headband visible, and Hidan's headband does not correspond to any known village.

and each seems to have some special significance; Tobibelieves that he can become a member after finding Sasori's ring, and although Zetsu claims it's not as easy as that, Tobi does indeed become a member. Deidara reinforces the significance of the rings when, after losing both his arms, he expresses more concern for finding the ring than finding the arm itself. Likewise, when Orochimaru leaves the organization he takes his ring with him, and in the ten years since then he has yet to be replaced. Each ring bears a unique symbol, the first kanji of its name.

; Kakuzu, for example, joined because it makes it easier for him to collect bounties. Soon after the start of the series, however, Akatsuki becomes increasingly more active as its members start to carry out the tasks needed to achieve their ultimate goal: domination over the Naruto world. The leader, Pain, has created a three-step process to work their way towards this goal. First, they plan to obtain a large amount of money to support their organization. Second, they plan to set up a mercenary group loyal only to Akatsuki. To build their reputation, they plan to accept any mission below the usual cost and operate off of the excess funds earned in the first part of their plan. Because there haven't been any wars in some time, the established shinobi villages can't afford to charge such low prices, leading the smaller countries to hire Akatsuki over the more expensive shinobi villages. By using the tailed beasts, Akatsuki can start wars and then immediately quell them, solidifying their reputation and convincing every country to depend on them. Without any business, the other shinobi villages would collapse due to a lack of funds. Finally, after Akatsuki is the only major shinobi force in existence, they could easily conquer the other countries. Despite the severity of this plan, members do not automatically learn of it upon joining; Hidan did not find out about it until asking.
The tailed beasts, nine gigantic demons of immense power, are the focus of much of Akatsuki's effort and screen time within the series. Each Akatsuki member is assigned to capture alive one of the nine beasts or, in most cases, the person that beast has been sealed into. Akatsuki has so far obtained seven of the nine: the One-Tailed Shukaku, the Two-Tailed Demon Cat, the three-tailed beast, the four-tailed beast, and three others.
Once one of the demons has been captured it is taken to the nearest Akatsuki lair where
the remaining members then assemble through astral projection. Pain summons a giant statue of a humanoid monster while the beast or its host is placed before it. The members then take their place on the finger of the statue that corresponds to their respective ring, and the group prepares to seal the beast into the statue. For the sealing, nine dragon-like effigies pour from the statue's mouth to surround the captured host, forcefully remove the tailed beast from them, and seal it into the statue. In the case of an unsealed tailed beast, the same thing happens to the beast itself. The sealing process takes three days to complete. Kisame Hoshigaki notes that the demons must be sealed in a specific order, as he states that sealing the Nine-Tailed Demon Fox before the other eight beasts would destroy the statue. Tobi, the character shown giving Pain orders, hints that the tailed beasts have a purpose beyond global conquest, implying that acquiring all nine would allow his Sharingan to return to full power. Pain, however, has different plans on using the tailed beasts, wishing to use them to create a weapon of mass destruction that will force the world to learn the pointlessness of fighting and try to achieve a sense of world peace.

The Espada at the time of the group's introduction consists of nine males and one female. Each Espada member is chosen for their superior combat ability and then assigned a number from 1 to 10 that indicates their rank and relative power level, which is tattooed somewhere on their body (Grimmjow's is on his lower back, for instance). The Espada are given control over the Números and are regarded as the strongest arrancar in existence. Similar to the power gap between captains and lieutenants in the Gotei 13, the strength of the Espada far surpasses that of the average Número. As Aaroniero Arruruerie notes, all of the Espada except him were at least adjuchas-class menos before becoming arrancar.

They are assigned a two digit number at birth from 11 to 99 to indicate their age (Número 11 is the oldest, Número 99 is the youngest). The basic Número uniform consists of a white-collared jacket and robes held with a black sash. However, the uniform is customizable, giving each Número a sense of individuality. The fighting ability of Números is thought to be superior to all other arrancar, except for the Espada (current and former).

The number of Fracción for any given Espada varies: Stark and Nnoitra Jiruga would seem to have just one, while Szayel Aporro Granz has at least a dozen.

Being former Espada, they are far stronger than the normal Números. They reside in Tres Cifras, which translates literally from Spanish as "three digits". As mentioned by Dordonii, these former "naturally created" Espada were rendered obsolete after Aizen began artificially creating arrancar to meet his own standards.

True form-a fully-grown woman with longer hair but otherwise similar features
Her skull mask changes slightly
A large "3" tattooed on her back indicates that she was previously the 3rd Espada
Nel's initial ability is the power to swallow enemy attacks and fire them back with powerful force, indicated by the eyes on her skull mask glowing
Her vomit (which she believes to be saliva) also acts as a powerful healing agent
In her adult form, Nel's speed and strength are greatly increased, and her attack absorption ability is much easier for her to use

wears typical arrancar clothes: a white jacket, black sash, and a white hakama; however, his jacket has longer coat-tails than others
Espada number, four, signifying his rank amongst the Espada and level of power, is tattooed on the left side of his chest
He can use both cero and bala blasts, and can deflect attacks of similar power barehanded
He can also open garganta to move to and from Hueco Mundo

He is an extremely tall and lanky arrancar, black hair, wears an eyepatch, three bracelets on each wrist and his uniform includes an overblown and spoon-like hood
The Quinta Espada, making him the fifth most powerful arrancar under Aizen's command

Grimmjow appears to be a laid back and irreverent individual, but this scruffy appearance hides an impulsive, excessively violent personality and a lethally short temper
A crooked number 6 is tattooed on his back just above and to the right of his hollow hole

contemplative personality and rarely spoke
Using the eyes on his body, Zommari can take control of one object per eye

He is Yylfordt Granz's younger brother, although Szayel is much stronger
He is the scientist of the Espada, developing various spiritual equipment for use by the arrancar
He is also adept at creating devices that can manipulate and suppress spiritual power, as evidenced in his battle with Renji Abarai

In place of a normal head, he has a large, glass capsule filled with red liquid and two floating heads. The two heads tend to talk in tandem when revealed, giving the effect of two people speaking at once. Aaroniero also has the ability to broadcast information of whatever he is currently seeing or experiencing to other arrancar

What remains of his hollow mask is the jawbone, which rests on his chin. A tattoo of the number ten, signifying Yammy's rank and level of power amongst the Espada, is on his left shoulder. Not the most intelligent individual, he relies on his brute strength in battle, taking little interest in using his sword until he is overpowered. In addition to his strength, he makes use of cero and bala blasts, like many other high-class hollows and arrancar. He relies on his superior, Ulquiorra Schiffer, to explain things and give him orders while in battle

In comparison with the other arrancar, he has a more goofy personality, similar to Don Kanonji's. He is much more serious in battle

Despite her rather odd appearance, she has no qualms about pointing out when others have similar habits, as she does to Uryū Ishida. She also gets quite bothered if an enemy attacks her while she is talking

His outfit has been modified to match his particular style, including large frills on his collar and thighs. The remains of his hollow mask are a sunglasses-shaped plate on his forehead with four teeth coming out above each eye

Shawlong is an intellectual, or at least an analyst, able to confidently state the nature of his opponent's powers

What remains of his hollow mask is on the top of his head, and looks like a broken helmet. He commonly refers to other characters as "brother" when speaking. He was the older brother of Szayel Aporro Granz, the 8th Espada.

The right-hand side of his mask is wrapped in bandages, which obscures his right eye — the bandages are meant to hide an injury given to him by Grimmjow when he was still a menos

Though not an Espada, Soul Society ranks his spiritual power in the same class as them. Wonderweiss is small, thin, and somewhat child-like. What is left of his hollow mask remains on top of his head, and resembles a tiara or small crown.