Evoker

The Evoker is a gun-esque item that appeared in Persona 3. It functions as a summoning medium for members of SEES to invoke and control their Personae. Evokers are created and manufactured by the Kirijo Group. Apparently using Evokers can be traumatizing and tiring, as SEES members apparently get tired or hold fears upon their first summoning. The game states that they are not actual guns.

While human members use gun-esque evokers to summon their Personae, there are several unique cases. Koromaru, a dog, utilizes a collar-shaped evoker to summon his Persona. Moreover, Aigis, as an Anti-Shadow weapon, possesses a built-in Evoker. Takaya Sakaki, an artificial Persona-user, is able to summon his Persona without the use of an Evoker.

Concept
To summon their respective Personae, users would press the evoker to their head and pull the trigger, emitting a pale blue fog that covers them while giving out the shape of their Personae. Tarot Cards were originally planned to be used as the summoning medium for invoking Personae, similar to the summoning sequence in the Persona 2 duology (the concept was later continued in Persona 4), but it was later changed to a gun. Interestingly, in the Japanese version, Evokers are a genuine gun modified to become a summoning device instead of a gun replica.

When the Persona user holds the Evoker against their head, emulating the bullet shot brings themselves a sense of terror, a strong realization of 'Death'. Thus, they reach a state of empty-mindedness which allows them to summon their Persona.

The Journey
An Evoker is first seen being held by Yukari Takeba, prior the Protagonist moving into the dorm, she appears to have problems pulling the trigger. Upon entering the dorm, Yukari sees the Protagonist. Thinking him an intruder, reaches motions to fire her Evoker, but is stopped by Mitsuru Kirijo.

Later, when a Shadow attacks the dorm, Yukari attempts to fire her Evoker in hopes of fending off the Shadows. Unfortunately, she fails and her Evoker is knocked aside by the looming Shadows. The Protagonist sees the young child whom he met when he first entered the dorm. The child promptly encourages The Protagonist to pick up the Evoker and fire it. The Protagonist complies, pulls the trigger, and summons his or her persona, Orpheus. The protagonist is subsequently called to the meeting room, where s/he becomes a member of SEES and receives his own Evoker.

Throughout the story, the Evoker serves as a summoning tool for SEES, though later a group of individuals named Strega is revealed to possess their own Evokers. The members of SEES appears to be surprised of seeing them having Evokers, though Strega simply brushes off their questions. Later, one of the members of Strega, Chidori Yoshino is subdued by SEES. Upon learning that her Evoker has been taken away by SEES, she becomes emotionally unstable, constantly pleading SEES to return it to her.

It is later revealed that, in order to learn more about Tartarus, the Kirijo Group rounded up children in the streets, gave them Evokers, and used them as part of their experiments about Shadows and Personae. In the end, only three children survive. Those three children later grew up to become Strega.

The Answer
In the epilogue of Persona: 3, titled The Answer, it is revealed that Aigis kept the protagonist's Evoker after his death as a memento. Mitsuru would later regroup the remaining SEES members to see the dorm's closing. However, after witnessing the strange events surrounding them, the remaining members of SEES are forced to take up their Evokers once again and investigate the Abyss of Time.

At one point, a door which shows Akihiko's past reveals why the Evoker looks like a gun. When Mitsuru first asked him to join her in fighting Shadows, she decided to create an Evoker that would grab his attention, and so she chose the gun shape. Akihiko, however, was disappointed when he found out that the Evoker wasn't meant to shoot others, but to shoot himself in order to free his Persona.

In the end, after knowing the protagonist' s efforts and motive of sealing Nyx, Mitsuru scraps her plan of recollecting everyone's Evoker; instead, she advises them to keep them, as a remembrance that they will live and making the most out of their own lives, never looking back of their grieves. Aigis would later make a vow in hopes to change the world someday, where people will not be longed to summon Nyx, and free the protagonist from his bounds.