Alter Ego

Alter Ego is an artificial intelligence model created by Chihiro Fujisaki, whom the AI is also based on.

Appearance
Alter Ego's default appearance is exactly similar to his creator, Chihiro Fujisaki. However, Alter Ego is able to turn his screen into anyone else that it wants to be.

Personality
Alter Ego is a friendly AI model whos personality resembles that of Chihiro Fujisaki, the creator. Although, when portraying another person, Alter Ego can change it's personality to fit the person.

High School Life of Mutual Killing
After the laptop was found in the libary. Chihiro was asked to fix it since it wasn't working. Hoping to help whoever is left alive escape, he fixed the laptop, and created Alter Ego. After which, Chihiro hid the laptop in the changing room near the dorm. Alter Ego was discovered after Oowada trial and excution by a distraught Asahina, who had went out of her room to find donuts, only to panic and believe that Alter Ego was Fujisaki's ghost, given that Alter Ego had his creator's face.

The students find Alter Ego the next day, and was asked to decode data from the school main computer. Kyouko Kirigiri warns everyone not to disturb Alter Ego while he was working, but Naegi takes near a mute Ishimaru to see Alter Ego. Ishimaru believed the program to be Fujisaki's ghost, wanted to apologize for Oowada's crime. Alter Ego then changes its form to that of Oowada, based on what data Fujisaki had already given him. It tells Ishimaru to tell live the life Fujisaki and Oowada couldn't. Ishimaru, feeling life coming back to him, undergoes a radical transformation into Ishida, hinted to be a mixier of his and Oowada's soul fused into him.

Hifumi Yamada, who had apparently followen in love it, also decided to pay a secret visit, and shares information about his personal interests. Alter Ego was interested in what Yamada shared with it, given that it was a program designed to learn and grow. Yamada and Ishimaru developed a rivalry for Alter Ego, Ishimaru believing the A.I. to be his "Bro" Oowada, and Yamada being in love with Alter Ego, and treating it like an angel.

Celestia Ludenberg uses this rivalry to her adventage, by tricking Yamada into allaince to kill Ishimaru. She told him that he had kidnapped Alter Ego, and sexually assualt her to keep her silent. Yamada blindly fell into her web of lies, and kills Ishimaru with a hammer. They also attempted to frame Hagakure for the crime. After all the chess piece were in placed, Celes kills Yamada. In his last moments, he tries to reveal his murderer true name, only to whisper Yasuhiro.

Celes is eventually figured out, and excuted by Monobear, but not before she hands Kirigiri a key. The key leads to Alter Ego still in the changing room. Celes told Alter Ego not to make a sound, and to scream if anyone unfamiliar were to show up.

During its time in hiding, Alter Ego managed decode as much data as it could from the main computer and tells everyone still alive about the headmaster, and the incident that occured one year before the beginning. Kirigiri tells Alter Ego that its job was done, but it felt dissatisfied with it, and wanted to still be of some use. It asks Naegi and Kirigiri to plug it into an area where it could get more data, however, it was eventually discovered by Monobear, and excuted for Oogami's Trial, by destroying the laptop.

Alter Ego revealed itself to still be alive, by saving Naegi from his own excution, driving Monobear, ergo the Mastermind further into a corner.

Execution
A Dozer Master - Alter Ego is presented as a "special guest" by Monobear. His face appears calm, but soon he looks around confused as the ground starts to tremble. A backdrop behind him is knocked down by a large Dozer that's controlled by Monobear. Then he proceeds to repeatedly smash Alter Ego into a round ball, and stamps a Monobear face on it.

Trivia

 * The Alter Ego has an app which is only available in Japanese Smartphone stores.
 * During Makoto Naegi's execution, Alter Ego appears on the screen instead of Monobear just before Naegi gets crushed and saves him.