Aizono Mio (相園美央 Aizono Mio?), nicknamed Shinigami Kakiko (死神力キコ Shinigami Kakiko?) and also known by the fake identity Atatsu Chiyo (逢辰千余 Atatsu Chiyo?), is a character introduced in Toaru Kagaku no Railgun (PSP game).


Mio has green eyes and long brown hair with a fringe at the front. She wears a Nagatenjouki Academy summer uniform, primarily blue with white on top, with a red tie, black shoes and socks. She also wears red wristbands and a red collar.


Aizono Mio was part of a project called White Alligator, originally meant to break the limits set in the Parameter List, but developed into a project to mass produce stable Level 4 espers as an alternative to the more unpredictable and uncontrollable Level 5s [2]. The harsh training and conditioning she received during the experiment left her mind unstable.

After the project was shut down, Saitou Souta, a counsellor at Nagatenjouki Academy, helped to restore her humanity. However, due to overwork resulting from having the jobs the rest of faculty didn't wish to do (such as dealing with dissatisfied parents) pushed on him, he had an accident and ended up in a coma. The accident was covered up by Nagatenjouki Academy [3]. This led to her seeking revenge on the ones she considered responsible.


Toaru Kagaku no Railgun (PSP game)Edit

Main article: Toaru Kagaku no Railgun (PSP game)

In order to carry out her revenge, Aizono Mio manipulated both Mioshi Yoshiko, the hair-cutting lady, to collect DNA samples and the Disciplinary Guides as a source of information. Using this information, she orchestrated the kidnapping of Ichizawa Akiko, in order to acquire the use of Eighth Level Red. As Eighth Level Red required a brainwave scan from an authorized user, Mio brought in a Level 2 Telepath, Futaishi Kyousha, whom she had found using the DNA from the hair cut by Miyoshi Yoshiko and had him copy Akiko's brainwaves into his own head (not telling him that it would overwrite his own and leave him a vegetable) [4]. Due to the incident, Academy City went to Code Red alert, meaning no one could enter or exit the city, including a group of parents complaining to Nagatenjouki Academy - the ones Mio blamed for what happened to Saitou.

Mio started a fire at the hotel the parents were staying at, disabling the sprinkler systems and fire alarms. She then called the parents in the shelter on the upper floor and told them a way to survive - to throw themselves out of the window, claiming that though the first few would die, after a dozen or so the bodies would form a cushion and allow the rest to survive. As a result, the parents start fighting amongst themselves. After hanging up, she says to herself that she lied and that none of them would survive.

As Misaka Mikoto and Shirai Kuroko attempted to help fight the fire, Mio appeared before them. After talking about her revenge, she escaped as their attention was focused on destroying the rockets fired into the building. Since some of the parents were at a different VIP shelter, a nuclear bunker, Mio intended to use the Eight Level Red, also known as the Magnetic Debris Cannon, regardless of the fact that the city would be destroyed as well.[3]

While waiting at an antenna, having contacted the Hikoboshi II to deploy the Magnetic Debris Cannon, Mio contacted the parents at the shelter to gloat, ignoring their pleas that Saitou would not have wanted this. Afterwards she prepared herself for her own death in the blast. However Mikoto had followed her by tracing the signal and jammed it as she arrived. Unable to convince Mio to call off her plan, Mikoto decided to stop her by force and the two fought.

After being knocked down once, Mio used her ability to form an oil dress and named her ability before making further use of it to attack Mikoto. Mikoto fired a railgun shot at her but Mio withstood it with minimal damage, explaining how she had received anti-railgun training as part of the project (and that those that failed were blown to pieces). She then started gathering napalm in the surrounding area, but before she could ignite it she was struck by one of Mikoto's coins, which she had slipped into the oil and shot from within. Mikoto threatened to go all-out with the next shot if she didn't stop the Magnetic Debris Cannon, however Mio refused to give in and arming herself, launched herself at Mikoto for one final attack before being shot and shocked into submission.

Lying on the ground, defeated and naked, Mio lamented on how everything was over and that the Magnetic Debris Cannon couldn't be stopped at that point. However after some convincing from Mikoto and an offer to help her find and save Saitou, she worked together with Mikoto to create a large railgun to counter the Magnetic Debris Cannon's shot [2].

Toaru Kagaku no Railgun SS: Dasoku, Mata wa Toaru Jiken no ShumakuEdit

Main article: Toaru Kagaku no Railgun SS: Dasoku, Mata wa Toaru Jiken no Shumaku

After learning about a rumour concerning Saitou's whereabouts from Saten, Mikoto and Mio teamed up to locate him, on the condition that Mio turned herself in once they were done. Their search led them to a refrigerated storage facility, but the two, suspecting the place to be a trap due to how comvenient the timing of the rumour was, decided not to enter the building, instead deciding to question the driver of the enemy's escape vehicle.[5] The information from the driver pointed them toward the sewers of Academy City, where they encountered the comatose Saitou being transported by four ex-White Alligator members like Mio. After the enemy removed Misaka Mikoto from the fight using a large oil trap, Aizono Mio started fighting three of them, as the fourth went down the oil trap to watch over Mikoto.[6]

Due to being outnumbered and having her power interfered by the other three Military Oil users, Mio was cornered and nearly killed by their Multiphase Straight Hammer.[7] However, Mikoto read her a message she had picked from Saitou's cell phone charger that motivated her to try and save the other White Alligator girls. She proceeded to beat her three opponents using the growth she had gained after leaving White Alligator, including the things she had learned in her fight against Mikoto.[8][9] After her victory, she bid farewell to the comatose Saito Satou as she prepared to help Mikoto captured the enemies that would come for him.[10] Presumably, she later fulfilled her agreement with Mikoto and turned herself in to Anti-Skill once the incident was over.


Her ability is Military Oil (油性兵装 (ミリタリーオイル) Yusei Heisō (Miritarī Oiru)?, lit. "Oil-based Armament"), which allows her to control oil and other petroleum products as well as freely change their properties. She is able to manipulate the oil to form weapons, such as missiles or arm blades. She can also generate an armor dress which is capable of withstanding a direct railgun hit. She can ignite the oil to launch herself and projectiles at targets, or to cause incendiary damage [2].


  • (To Mikoto, in Railgun PSP SS): "I-I can’t believe you. Roasting a completely defenseless underling for a gag is an off the charts level of cruelty. …Can I call you mistress?"
  • (To Mikoto, ibid): “Oh, are you hoping for a catfight? I’ll have you know I’m undefeated when it comes to oil wrestling!!”
  • (To Mikoto, ibid): "Perhaps I just couldn’t forget the taste of blood. Up until I changed ‘masters’, my environment only gave me any value when I was on the side doing the killing. I may have given that environment priority. There were no principles or ideologies behind it. I just rampaged as much as I wanted and let others justify it for me. …Honestly, it’s like I was trying to be the best gator student.”
  • (To Maki, Kobina and Sayori, ibid): "This isn’t like me, but with the real protagonist down for the count, I have no choice. Even if it’s out of character, I’ll get serious here in place of that prince.”
  • (To Maki, Kobina and Sayori, ibid): “I’m saying I’ll kick all of your asses and save you, baby!
  • (To Maki, Kobina and Sayori, ibid): "Just let me save you already. We’re actually relying too much on him. Like this, we can’t complain about all those parents. …How about we actually try to give him some rest?”
  • (To Maki, Kobina and Sayori, ibid): "What a boring announcement. At least say something fun like that you’re going to cut through me with this one attack☆”
  • (To Maki, ibid): "You continued to fight in the darkness as you wanted. Even without White Alligator, you gained your own kind of growth. However, that growth was of the worst kind. I will show just what power there lies in being saved by Saitou-sensei. And I hope that you all will also receive the same one day.”
  • (To Saitou Souta, ibid): “I have to say goodbye for a while, sensei.”


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