Mei is a young priestess who is a descendant of the Azure Shrine Maiden. Her family have been protecting the Wadatsumi area for generations to prevent the resurrection of the Black Beast. Her parents were present at the Wadatsumi Incident and the birth of Hinata Himezuru. During this incident, her mother disappeared and her father had his soul drained but his body was still left intact. The Amanohokosaka's later sold the Wadatsumi area to Takamagahara.
Since her father's body was still technically alive, she made a deal with the Mitsurugi Institute; she would help the Institute in the Wadatsumi area as long as they kept his body alive, however, this is no use due to his lack of soul, making him, in a sense, dead. The deal also allowed her access to the area. Mei has a huge distrust and hate for the Magic Guild after they attempted to bring down the Amanohokosaka family by making them lose money and trust. She visits her father daily in hospital, and has formed a firm relationship with the staff members there, including Yuki Himezuru.
First appearing alongside Sōichirō Unomaru and Es in the Himezuru residence, Mei talked to Tōya and described the existence of Unions and the Mitsurugi Agency to him. Afterwards, she and Sōichirō talked in the car, having delivered their warnings. She told him that she had indeed felt a faint presence of the Azure.
Some time later, Mei found Es and Tōya on the rooftop of Hakuou North Academy, explaining that she had been a member of the school for several months. After a little deliberation, she placed the Goofball Proximity Survejor on his forehead so she could monitor him, making sure that he wouldn't be unable to be found. Work soon called for her, and she left. On the way to school the next day, she heard that a young mage was staying with Tōya - she discovered the mage's name is Kuon Glamred Stroheim, and openly shouted that she, herself, would do a much better job protecting the young man than Kuon could.
In the evening of the same day, Mei was called to a murder scene, where she found the dead body of Akio Osafune. Tōya and Es bumped into her, and she explained the situation to the both of them, telling them both that the Union had been murdered by the serial killer Ripper - several moments later, they were attacked by the very man himself. Mei tried to hold him back by using her Shikigami Raven spell, but to no avail, watching as the Union fled after his crazy attack. She ordered Es to follow the Union while she and Tōya caught up; sensing they wouldn't make it in time to back Es up, Mei used her magic to fly, startling Tōya as she took him with her. Once they found where Es and Ripper were, they landed at their location, jumping into the fray. There, the presence of Tōya scared away Ripper, leaving the duo alone with Es, and Kazuto Kotetsu, the recently arrived bounty hunter. Mei immediately clashed with Kazuto, to have Tōya pathetically come to her rescue, getting knocked out by the bounty hunter for his rudeness. Calmly telling Es to back down, Mei watched as Kazuto left, and then left herself, having had enough for one night.
Giving into Sōichirō's constant pestering, Mei went to the local pool, coldly greeting Tōya when she arrived. Afterwards, she formally introduced herself to Kuon and the two ended up in an intense argument, with Mei leaving on the note that she was Kuon's superior, and that she had better remember it. The following day, Mei decided to go to the rooftop of the school for lunch, feeling that the isolation would give her time to blog and use the Internet. As she made her way up, she eavesdropped on Kuon and Tōya's talk about anime, insulting Kuon's tastes and criticizing Tōya's lack of interest in the subject. Unfortunately, she exposed herself and quickly fled after they questioned why she was there. Once Akira Kamewari had gone missing, Mei did her best to help the others in finding him.
Arriving back at the Himezuru residence some nights later, Mei was shocked to see that Akira had undergone a transformation into a Union, and issued him a direct warning before he fled. She was introduced to Elise von Klagen, and, strangely, got along with her. The trio took Hinata, Es and Tōya to their beds to rest after their encounter with Akira; afterwards, Mei explained a little about the existence of them and the next course of action, but withheld some information, leaving a little afterwards.
She found Tōya attempting to escape while Es was on her break, and the two went to the Maha☆Raja~ Curry Shop. There, Mei was shocked to see Ringo Akagi, immediately (and correctly) assuming that she was Zwei of the Ten Sages. She dismissed her accusation after deducting that there was no chance that Zwei would be working in a random curry restaurant. Tōya lead Mei over to a seat and the two talked, the topic being Mei's ancestor, the Azure Shrine Maiden. She explained about her, and the existence of the Boundary, and of seithr. A little while later, Es came to pick up Tōya, leaving Mei to return home by herself.
Receiving a call from Kuon, Mei and Es rushed over to an unfinished building site, finding that Hinata had been kidnapped by Ripper. Mei rushed to the top of the building, watching on as Tōya lost control of the Original Grimoire. Thanks to Es having rescued Hinata, the young man calmed down, leaving Mei to order Es to take Hinata back home so she could rest. When they left, Sechs and Drei suddenly appeared, issuing a warning to them both about the Grimoire and the real intentions of Sōichirō - how he planned to control the minds of the entire world with the T-system; the two Sages left as they told the young women how they planned to destroy the Embryo. Tōya woke up a little afterwards, leaving the two magic users to take him home.
At the Himezuru household, Mei and Kuon told Tōya about how he went insane when he unleashed the power of the Grimoire, while doing so, Mei also thoroughly explained the full story of her ancestor, going on to explain her noble sacrifice in full. After discussing the power of the Original Grimoire, Kuon announced that she would not be coming back, and left to finish her mission. Mei attempted to stop Tōya from pursuing her, but could do little to stand in his way. She received a call from Sōichirō not long afterwards.
Sōichirō had deemed Tōya a high risk Union, and put Mei in charge of a squadron sent to detain him. She eventually found him and Es, and attempted to persuade them both to give up quietly. The two of them proved to be awkward, so Mei, having had enough, told them both that she quit. She told the duo to escape into the sewers while she bought time for them; a little later on, she met them as they exited the underground labyrinth, giving Es fresh clothes and escorting them back to the Himezuru household. Back there, she found Kuon, and teased her for the dramatic speech she made earlier about not returning. However, the group jumped into the discussion of what to do next, listening to Kuon's letter she received from Elise that detailed the events of the Wadatsumi Incident. Hinata arrived a little afterwards with food for everyone to replenish themselves on, and the group of Mei, Kuon, Es, and Tōya, left for the Restricted Ward to end the T-system to save the world.
Mei served as the guide inside the Ward, and they soon encountered Acht of the Ten Sages. Mei and Kuon convinced Tōya to go on ahead while they dealt with the Sage. After some deliberation, they also managed to get Es to pursue him and protect him. Despite using a vast amount of magic, the duo could not land a single hit on Acht due to her impressive skills. However, Mei came up with a solution to disable the Sage's Drive by using her last G.P.S charm; finding her way into Acht's defenses, Mei planted the charm on her, and the two magic users were finally able to land attack after attack on her. Several spells later, Mei and Kuon had knocked Acht into her final Phase, watching on as she dissolved into seithr.
Inside the hallways of the Takamagahara Wadatsumi Laboratory, Mei and Kuon found Es in the middle of battling several Es-N units. Coming to her rescue, the two of them fought the units to allow Es to go in the lower floors - after a difficult battle, the two of them managed to destroy the units and descended into the lower levels to find Tōya, coming to his and Es' aide as they battled Sechs; unfortunately, the both of them were cast aside by the Sage's overwhelming power.
After Sechs was defeated, Mei adopted the last Es-N unit to help her track down the remaining Drive-Infected Patients and give them proper treatment. This became something of a regular job, as she did so after school every-so-often with Tōya.
Some time after the events in XBlaze, Mei rose to become the head of the Amanohokosaka Clan. When Saya Terumi slaughtered everyone in the Terumi Clan, Mei and other members of the clan had her bound for five years until they could no longer contain her. She sent a letter to her relative, Naoto Kurogane, in order to explain the situation. The letter stated: "We can no longer bind Saya down here. You must kill her on your own. P.S. you went and died on your own, didn't you. You idiot!".
In Chronophantasma, it is revealed that Tenjō Amanohokosaka and Homura Amanohokosaka are her descendants.
Mei is a mature young girl with long purple hair styled in a hime cut and eyes. She wears dark-colored Japanese style Gothic heavy dress-like outfit with a matching cap with skull, dark purple jacket, and black leather boots.
At the pool, Mei wears her hair up in a small black bow, and wears a relatively simple black bikini. On her wrists are strapped with spiked black belts. While attending school, Mei wears the navy style uniform with a gray skirt and black leggings - because she is a first year, she wears a blue ribbon on the front.
In Lost: Memories, Mei began to wear purple and white ribbons on the front of her hair.
Personality-wise, Mei is hostile to all she meets. She is extremely hostile towards Kuon Glamred Stroheim due to her being from the Magic Guild. However, this usual hostility that is presented to everyone can usually be avoided by presenting excellent manners, and treating Mei as a pampered princess. Yet, despite this hostility, she and Kuon overcome their differences bonding over their tragedies of having lost a parent. The both of them argue constantly, but they remain firm friends despite this. Like many a teenager, Mei frequently blogs, and has been known to use text speech when updating her TOi; on top of this, she is an avid anime watcher, and is critical of what others watch, suggesting that Kuon watches 'B-tier slice-of-life crap'.
Underneath her hypercritical attitude, Mei is secretly quite caring of those around her, especially with family - effectively surrendering her freedom to the whims of the Mitsurugi Agency just so her family could live on. She visits her father in hospital everyday, becoming a favorite among the constant visitors and staff members. When angered, Mei has been known to swear in a colorful manner.
Age seems to have mellowed her, as she was unwilling to kill Saya Terumi despite the fact she murdered a large portion of her family. However, she still retains her tendency to insult others casually, such as Naoto Kurogane.
Powers and Abilities
Being the direct descendent of the Azure Shrine Maiden, Mei can sense the Azure's power, but due to her thin bloodine, this power is weak. Mei also has an ability called Shikigami Raven, which releases a large, raven-like creature; anyone who touches the raven is completely immobilized. Mei is also fairly talented with charms, being able to enhance an Amanohokosaka Clan charm and turn it into the Goffball Proximity Survejor, a device which helped turn the tide in a battle against Acht of the Ten Sages. Further demonstrating her excellency as an Exorcist, Mei can fly, and even carry someone else alongside her while doing so. In her own route, Mei gains the ability to use the Drive Blood Cain (血契封 Buraddo Kain, Blood Vow Seal) to seal the Original Grimoire.