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Alert1 Spoiler Alert: This article/section contains details about future plot lines described in the light novels, not covered in the anime. Do not proceed unless you want to be spoiled.

Irregular (人工精霊イレギュラー, Iregyurā?. lit. "Artificial Spirit") is a new race introduced in Date A Live: Arusu Install. In the English release of the game, Irregulars are called AI Spirits. Only two such Spirits are known to exist: Maria Arusu and Marina Arusu.


The term is first mentioned by Kotori after an unforeseen error causes Shido to become trapped in a virtual reality dating game called Fall in Love My Little Shido 2 shortly after encountering a mysterious girl who shouldn't exist in the game's program. The possibility of hacking was raised, but due to the game being run using a Realizer through the Fraxinus's own systems, Reine stated that it was impossible for a human to possibly hack in. Following her logic, Kotori raised the possibility that the hacker is a Spirit, to which Reine replies that though the being had the powers of a Spirit, it existed only in the form of data, with no physical body of its own. Kotori then coins the term to describe the unknown being.


It is eventually revealed that the first Irregular, or AI Spirit, was created by Isaac Westcott, as seen during the game's opening scene. This Spirit was Marina Arusu, who was created in order to breach the Fraxinus's otherwise impenetrable cyber defenses. Marina was able to destroy some of the Fraxinu's protections and slip inside. Detecting the intrusion, the Fraxinus AI system managed to trap Marina inside the virtual world with a poweful firewall to protect the Fraxinus's main computer.

Seemingly using Marina's own design as a template, another version of Arusu, who Shido names Maria, appeared within the game, having been formed from the Fraxinus's control AI itself. Cut off from the main computer, Maria had lost most of her memories, only retaining her information on the Shido and the Spirits, together with her programmed function to foster love. The latter was the cause of her desire to understand what love was.

Maria continues to run the firewall protecting the Fraxinus subconsciously, keeping Marina trapped. This also prevented Shido and the other girls from leaving. Marina realized that if Maria were to gain human emotions, she might drop her guard long enough for Marina to seize control. She therefore encourages Shido to teach Maria about love.


  • It is never explicitly mentioned how Westcott created Marina or how the Fraxinus was able to copy her to create Maria.
  • Marina's design was later used as a basis for Nibelcole, another artificial Spirit produced by Westcott. Maria's design was later reused when Nia Honjo used her Angel to give form to the Frxinus AI, MARIA.
    • Notably, both reappearances were accomplished using power derived from Nia. Moreover, all of the designs use a nun theme for their standard appearances, similar to Nia's own Astral Dress.