|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.|
|“||Unn...that's right. I'm Arusu. But, I guess...... You can also say that I'm not Arusu?||”|
—Arusu Marina, to Shido Itsuka
|Hair Color||Black to white gradient|
|Affiliations||Deus Ex Machina Industries (Formerly)|
|Novel Debut||Date A Live: Ars Install (Novel)|
|Game Debut||Date A Live: Ars Install|
Marina has long, black to white gradient hair and a pair of golden eyes. Like Maria, she also wears an outfit similar to a western nun's. While Maria wears a white colored outfit, Marina, in contrast to that color, wears a black colored outfit instead and a gold, cross-like symbol on the hip part.
She has shown to be a little bit harsh and mean, as she always removes NPCs that are in her way without much thought. But as time went, she began to show signs that "she’s beginning to change" by helping an elderly NPC in the street. In the true route, Shido gives her a meat bun in a park at night, and at some other time, pats her head as a reward.
Marina is an artificial Spirit created by DEM Industries and was originally sent by them to take control of <Fraxinus>. She gets trapped in the game world and is waiting for Maria to weaken so she could take over Maria’s ‘authority’. She keeps watching as Maria keeps resetting the world to learn about love.
She does manage to take 90% of the authority after Shido finally kisses Maria. She then takes control of <Fraxinus>, charges the main cannon and prepares to shoot at Tenguu City. She is in the ‘Mother Room’ and Shido and the others head towards her. Marina makes multiple copies of herself so that the Spirits will fight against them while Shido and Maria go to the Mother Room. In the Mother Room, Marina pretends to befriend Maria with trying to shake her hand as a sign of friendship, and then takes the last 10% of her authority. She is then being able to create her Astral Dress. She keeps attacking while Shido uses the Spirits’ powers to protect Maria. Maria then prays for power to help Shido and somehow is able to create her Astral Dress as well, also getting back some of her authority. Shido then defeats Marina with Maria’s support.
Marina’s Astral Dress then goes wild and becomes a giant black ball that quickly regenerates when attacked. It also causes a problem at the outside as <Fraxinus> is now losing flight power and slowly falling toward Tenguu city. Maria then goes on ahead as she is the only one that can enter inside the ball. Moments later, the other Spirits arrive and they destroy the ball together. Shido then rushes towards where Maria and Marina are. In the meantime, Maria and Marina share each other’s memories and "understand each other". When Shido arrives, both Maria and Marina wish for Shido to kill them so that <Fraxinus> can fully restart, preventing it from falling towards Tenguu city and kill many people. After much resistance, Shido finally uses <Sandalphon> to break Marina’s crystal and thus she dies. After Maria disappears, Shido and the others then are able to get back to the real world as the crisis is already over.
In the true ending, it is revealed that Marina performed good deeds before her demise. She sent Maria’s mail message to Shido’s phone (in which Maria thought would be unreachable), and even installed Maria onto his phone, thereby allowing Maria to survive within his phone until she could be safely reinstalled into the Fraxinus.
- Light Novel
Power and Abilities
Astral Dress: Unnamed
Marina is shown to possess a power that is given name as:
- Copy [複製体（コピー）], Fukusei-tai , lit., "Body Replication"): This power is demonstrated by her during the beginning of the final battle with the other Spirits. Marina stated that by using this power allows her to make an unlimited copies of herself. She is shown to only use this power once, with the intention to distract the other Spirits while she went into the ‘Mother Room’. Marina did claim that she can fight all of them in that world even without that ability, but decides to use it since it is a bother for her to "play" with all of them. Reine notes that they are exact copies, although the real Marina is by far the strongest.
- You are here——in this world, whatever things you are going to do……how it's going to be, I'm looking forward to it. So, do a lot more things, bowl over me, choose——And, show me. The thing called as love of yours.
- "Itsuka Shido, your actions are hypocrisy. That's why you can't deny my power. Even from the start, you were not in a position to negotiate!" 
- "It's incredible that you throw yourself toward something that will only bring you pain... But you are someone unique who can seal and use the powers of the Spirits...Itsuka Shido. Your existence is also a contradiction." 
- "When you caressed my head... just a little, it made me happy. “Would it feel like this to be touched by someone from your family”, that's what I thought......" 
- "You're wrong. After all, I'm just an imitation. Someone like me... who isn't a human or a Spirit, is a normal girl? You make me laugh." 
- Like Rinne, Maria, and Rio, she doesn't have a number in her name.
- She is one of the two known Irregular Spirits in the game.
- The Nibelcole created by Westcott's <Beelzebub> are based on Marina's design.