A teenager who was orphaned as a young boy returns to the city of his childhood. Shortly after transferring to Gekkoukan High School, he is attacked by Shadows — creatures that feed on the minds of their victims. The assault awakens his Persona, Orpheus, his only chance at defeating these creatures of the night. He soon discovers that he shares this special ability with other students at his new school. From them he learns of the "Dark Hour," a hidden time that exists between one day and the next, swarming with Shadows. He joins the Specialized Extracurricular Execution Squad (SEES), and with his new friends, confronts the threat of the Shadows.After signing a contract in which he "accepts his fate of his own free will," the Main Character battles with the other members of SEES against the Greater Shadows, incarnations with traits and appearances similar to those of the first twelve Major Arcana of the Tarot. While this is occurring, he continues to encounter and eventually befriends the child who gave him the contract to sign at the very beginning of the game, an entity who refers to himself as Pharos, and who is really the incarnation of Death, the thirteenth Arcana.

A Persona is a second soul that dwells deep within a person's heart. It is an entirely different personality that emerges when a person is confronted with something from the outside world.
A Persona ability refers to the unique gift that enables a person to summon and use a Persona, Those who are capable of this feat are known as Persona-users. This ability is humanity's only hope to defeat the Shadows.

The Persona-users:
ALERT: descriptions contains a spoiler in each character

Minato Arisato (The Hero)
Persona: Orpheus of The Fool arcanum, Thanatos of The Death arcanum, Messiah of The Judgement arcanum.
The main character who has recently transferred to a new high school. After settling into his room in the dormitory, he is attacked by Shadows. This incident awakens his Persona ability . However, unlike the other SEES, the main character can use more than one Persona. Because of his special gift, he is chosen to lead the squad in the fight against the Shadows.It is eventually revealed that Aigis sealed Death within the Main Character when he was a young boy. If she had not, Death would have summoned Nyx and destroyed the world. Death became the entity known as Pharos while trapped in the Main Character's mind. The Main Character was subconsciously drawn to Gekkoukan High School since that is where Death can be revived.

Yukari Takeba
Persona: Io, Isis of The Lovers arcanum.
Yukari is a classmate of the main character, who lives in the same dormitory. Yukari is able to summon her own Persona and has been a member of SEES for quite sometime. She is strong-willed, but everyone loves her cheerfulness and positive outlook on life. However, there is more to Yukari than meets the eye. Though she's outwardly extraverted, she doesn't really let anyone get close to her. She constantly picks on Junpei, hides her true motives from the group, and represses a lot of anger and pain about her past.It turns out that Yukari has been alone for quite some time. Her father died a mysterious death a decade ago, and her mother neglects her in favor of her new boyfriends. Midway through the game, Yukari discovers that her father was involved in the incident that unleashed the Shadows upon the world. She is forced to face her anger and overcome it, and ends up fighting for her friends and her father's memory. She is no longer alone.

Junpei Iori
Persona: Hermes, Trismegistus of The Magician arcanum.
Junpei is in the same class as Yukari and Minato. He was the first student to speak with Minato after he transferred to Gekkoukan High School. He's a class clown who joined SEES after realizing his ability.He was found crying in a convenience store during the Dark Hour, and did not realize that he had the potential to call a Persona until Akihiko told him about it. His decision to join SEES was a swift one, and he immediately moved into their dorm, to Yukari’s dismay.Initially, Junpei fights because playing hero makes him feel like less of a loser. He uses his place in SEES to prop up his self-esteem, neglects his classwork, and snaps at the Main Character out of jealousy over his unique Persona abilities. Junpei only becomes more serious after he meets the Strega member Chidori. They fall for each other, and though she continues to fight SEES, eventually her loyalty to Takaya and fear of death conflict with her feelings for Junpei. When Takaya fatally attacks Junpei, Chidori sacrifices her life to save his and gives him some of her regenerative power. After her death Junpei becomes a focussed and determined young man.

Akihiko Sanada
Persona: Polydeuces, Caesar of The Emperor arcanum.
Akihiko is the captain of the school's boxing team. Outwardly he appears calm, cool, and collected, but on the inside he is full of passion and ambition. He views his membership in SEES as an opportunity for training.Akihiko was one of the three Persona users who originally founded SEES, alongside Mitsuru and Shinjiro. He and Shinjiro were close friends as children, having grown up in an orphanage together with Akihiko's now-deceased sister Miki. However, one night when the two were chasing down a Shadow, Shinjiro’s Persona went out of control and an innocent bystander was killed. The bystander was Ken Amada’s mother.After the incident, Shinjiro left SEES and his friendship with Akihiko became strained. The two only reconnect when Ken joins SEES, and Akihiko convinces Shinjiro to rejoin the group in order to protect him.When Akihiko realizes that Ken only volunteered for SEES as a means to get revenge on Shinjiro, he tries to save both of them from making grave mistakes, but he arrives too late. Though Ken lets go of his vendetta, Shinjiro is fatally shot while protecting him from Takaya. In the end, Shinjiro’s way of facing death head on gave Akihiko the courage to carry on in spite of all his losses. Akihiko is determined that Shinjiro's death not be in vain and to be just as fearless in the face of his own mortality. He is the character that is the least upset and conflicted about the impossible odds of fighting Nyx.

Mitsuru Kirijo
Persona: Penthesilea, Artemisia of The Empress arcanum.
Mitsuru is the president of the student council. She comes from the prestigious family that controls the powerful Kirijo Group. She is intelligent and commanding - both ideal qualities to provide support to the other SEES members.Mitsuru has been battling Shadows for a long time. Upon discovering of the Main Character’s potential as a Persona-user, she, along with Ikutsuki, invites him into SEES. At the beginning of the game she stays behind as a Support character, offering analysis and advice. She joins the party in battle only after the discovery of Fuuka Yamagishi, whose analysis power is much stronger than Mitsuru's.Throughout the game, Mitsuru hides many details about Tartarus and the Dark Hour from the group, due to feelings of guilt over her family's involvement in the accident that created them. Since it was her grandfather who was responsible for everything, she feels that the problem rests on her shoulders. After Ikutsuki kills her father, she loses all her will to fight, since restoring the family honor is meaningless without a family. Fortunately, Mitsuru regains her resolve thanks to some intervention from Yukari.

Aigis
Persona: Palladion, Athena of The Chariot arcanum.
Aigis is the last remainder of the Anti-Shadow Weapon created by the Kirijo Group. It seems that her mission is not only to destroy Shadows but also to protect Minato from harm.During her battle with Ryoji on the Moonlight Bridge, Aigis regains the memories trapped in her damaged circuits. The player learns that, ten years before the game, she was tasked to defeat or seal away Death so that the coming of Nyx would be averted. Since she was unable to defeat Death, she sealed the entity away in a young boy who was the sole survivor of a nearby car crash. That young boy was the Main Character. She is driven to protect him both to try and suppress Death and because she feels a great deal of guilt over her actions.Aigis is damaged during her fight with Ryoji and must be repaired by the Kirijo Group. When she returns she shows more human-like qualities and emotions, and decides to stand against the power of Nyx with her friends in SEES. After the final encounter with Nyx, she is the only one who remembers Tartarus, the Dark Hour, and the Main Character's sacrifice during his borrowed month of life. She allows him to live like a normal student for the few precious weeks that he has. Then, on Graduation Day, she holds the Main Character as he drifts into his final sleep, and swears that she will live her life protecting him.

Fuuka Yamagishi
Persona: Lucia, Juno of The Priestess arcanum.
Fuuka is one of the schoolmates of Minato, consider that she is a student of Gekkoukan High and is in a different classroom. She is known to be shy, sickly, and outspoken; this tends the other students to bully her.A few months into the school year, Fuuka goes missing for several days. Yukari, Junpei, and the Main Character decide to investigate after strange things start happening to girls who once bullied Fuuka. It turns out that the girls locked Fuuka up in the school gymnasium, where she accidentally became trapped in Tartarus. SEES takes part in a dangerous mission to rescue her.In Tartarus, Fuuka is awakened to the reality of her Persona power. At the same time, Natsuki, one of the girls who bullied Fuuka, wanders into the school to see if Fuuka is alright. Fuuka who ends up saving Natsuki in spite of all that Natsuki did to her, and they both become fast friends afterwards even though Natsuki has no memory of the incident. Under Natsuki and SEES' influence, Fuuka changes from a shy and isolated girl into a strong-willed, compassionate young woman. Both her Persona and her hacking skills manifest her desire to always be connected to her friends.

Ken Amada
Persona: Nemesis, Kala-Nemi of Justice arcanum.
Ken is the youngest member who joined SEES during summer break. He is mature, and precocious that he doesn't even act like his own age. Ken's intentions of joining SEES may not be the same as the others but may far greater.Ken's mother was accidentally killed by Shinjiro during a SEES mission, and Ken infiltrates SEES in order to kill him.During Ken's confrontation with Shinjiro, Takaya intervenes and reveals that Ken has been planning to commit suicide after killing Shinjiro. He also reveals that Strega has been supplying Shinjiro with special drugs to control his Persona, and that the drugs will soon kill him. This completely shatters Ken’s hopes of revenge. After a brief fight between Shinjiro and Takaya, the Strega leader takes a shot at Ken. Shinjiro jumps in front of the bullet. Dying, he reminds Ken that he is still a child with a whole life ahead of him and a future that can be about more than vengeance. Shinjiro's last words inspire Ken to fight for the future his mother would have wanted for him.

Koromaru
Persona: Cerberus of Strength arcanum.
Koromaru's master was killed in an incident involving Shadows. He became a stray, and was watched over by Fuuka and Yukari. Koromaru remains faithful to his master even after his death, retracing the path of their old walks and revisiting the place where he was slain. One day when Akihiko is hunting Shadows, he comes across the canine, who is gravely injured. The Shadows surrounding him are dead. Once Koromaru is healed, Ikutsuki reveals that he too has the potential to summon a Persona.

Shinjiro Aragaki
Persona:Castor of The Hierophant arcanum
Shiniro, also known as Shinji, is a childhood friend of Akihiko and senior student of Gekkoukan High. Tough-talking foul-mouthed Shinjiro was once a member of SEES, alongside with Akihiko and Mitsuru. During one of their missions Shijiro's Persona went out of control and accidentally killed a bystander; Ken Amada's mother. He quits the group after the accident. When Akihiko persuades Shinjiro to rejoin the group he stubbornly declines his offer, but he rejoined after Akihiko told him that Ken is a Persona-user and joined SEES, he changed his mind and rejoined SEES. During a full moon, Ken invites Shinjiro at the alley, where Ken's mother was killed. Shinjiro has no intentions to resist to Ken's attempt to extract revenge, but warns the boy that if he carries, he could end up just like Shinjiro. As Ken struggles to go through with his plan, the two are interrupted by Takaya. Takaya takes a shot at Ken and Shinjiro jumps in front of the bullet, ending his own life. He earns Ken's respect and inspires Akihiko's resolve with this final sacrifice.

The description of the minato and the rest (akihiko, mistsuru, junpei and yukari) are taken from the guidebook (i thinks it is a guidebook) when you buy the persona 3 game

you may also add something about the character or anything.