Mayuri Shiina (椎名 まゆり, Shīna Mayuri), also known as Mayushii☆, is Rintaro Okabe's childhood friend, a part-time worker at May Queen Nyan-nyan and a member of the Future Gadget Lab. She is also an avid cosplay maker and friend of Luka Urushibara and Akiha Rumiho.
Mayuri is a short girl with short black hair and light blue eyes. Her hair forms fringes that sweep from either side. Mayuri's eyebrows are noticeably thick.
Mayuri's outfit is simple and comfortable, consisting of a light blue one-piece dress and a hat of the same color. She also wears black leggings underneath her clothing.
When she attends to her work at May Queen Nyan-nyan, she wears a blonde wig tied into a long ponytail.
Mayuri possesses an extremely childish and naïve attitude for her age. While this may have something to do with her inability to accept the death of her grandmother when she was young, Okabe states at one point that she's always been a little bit different, though he never goes into any detail beyond this. Mayuri has a great fondness for cute things like Upa cushions, and likes to give cute nicknames to familiar people, like Okarin for Okabe, being a portmanteau of his last and first names Okabe Rintaro, even referring to herself as Mayushii, being a portmanteau of Mayuri Shiina.
Though appearing as one of the less intelligent members of the lab, according to Okabe, Mayuri is very perceptive, often being surprisingly quick to catch things no one else notices, and being good at understanding how others feel. Mayuri also does not question Daru's perverted comments and mannerisms, or is not in any way offended by them.
Despite being socially inept, she is also responsible for Rintaro's well-being, usually tending to his needs most of the time.
As a child, Mayuri was close friends with Rintaro Okabe, and they could often be seen together. However, after the death of her grandmother when Mayuri was 11, she entered a state of PTSD that caused her to be unable to talk to others, and could be seen in front of her grandmother's grave in the cemetery most of the time.
Out of fear that something could happen to her, Rintaro tried to call out to her while when she was in the cemetery. One day, as Mayuri raised her hand towards the sky after it stopped raining, Rintaro's fear reached its limit, and he rushed to hug her, proclaiming to be a "mad scientist" and that Mayuri was his "hostage", and that, therefore, she was not allowed to go away. Fortunately, his new persona he created helped her overcome her immense grief and went back to normal.
Shortly after Rintaro creates the Future Gadget Lab in 2010, Mayuri was the first one to join it, as she felt that Rintaro was lonely all by himself and wanted to be with him. For a few months, they both were the only ones to attend the lab, where they spent their time doing nothing of particular relevance. Some months later, Mayuri accidentally discovered the PhoneWave's hidden function, resulting in a bunch of gelified bananas, which she called "gelnanas".
On July 28, 2010, Mayuri attended alongside Rintaro Dr. Nakabachi's time machine seminar. Shortly before the seminar, she managed to win a rare metal Upa out of a slot machine, but lost it a few moments later. After Okabe changes the timeline with his mail to Daru, she accompanies him in RadiKan, to see the crashed satellite.
Mayuri decides to visit Luka, her friend from school, and try to convince him to do cosplay with an outfit she made, since Mayuri likes more to make outfits than to use them. As expected by her, Luka is embarrassed to do something like this, since it's a female outfit. Mayuri says the popular phrases around @chan: "Someone this cute can't possibly be a girl!" and "Cuteness is justice!", she also admires the relationship of master and disciple that Okabe and Luka have, getting excited although she says she's not a fujoshi.
She welcomes Okabe when he appears at May Queen Nyan-Nyan, the place where she and Faris work, and says that "Okarin" and welcome ("Okaeri" in japanese) go well together. She's the second most popular maid there due to her habit of guiding the clients by their hand. She guides Okabe to Daru's table and returns to work.
Mayuri appears later in the lab while Okabe and the others were doing experiments, and introduces herself to Kurisu when she joins the lab, saying she's glad that she's not the only female labmem now. However, she got angry that they were using the food she bought to eat later for experiments, and attempted to stop them by opening the PhoneWave while it was being used. This caused an electrical discharge to occur and she's grabbed by Okabe, who is afraid to lose her. They later find out that the message they sent was indeed sent to the past, but Mayuri find those things too complicated for her to understand and she leaves shortly after the discharge ocurred, still angry about the wasted food.
She sents a mail to Okabe about the money she uses to buy food, and he has the option to thank and promise her to buy anything she wants, which causes her to get really excited. She later finds out that Okabe and Daru were both awake for two nights, and decided to buy them some food, including Okabe's favorite udon.
After Okabe decides to hack SERN's database, Mayuri constantly complains that he is doing something wrong and decides against joining him in those type of acts.
As Okabe decides to leave the lab, Mayuri joins him asking them to have lunch. As they walk together Mayuri is suddenly nowhere to be seen, which scares Okabe. She stopped and extended her hand to the sky, her explanation is that she sometimes feels that she can reach the stars.
She calls Okabe while at work to inform him of something he wants to know. They eat on her break, and Mayuri says that she asked Faris about the IBN5100 and found out that she knows something about it.
After her work she returns the lab with Okabe and the others, but leaves shortly after.
As the Future Gadget Lab's experiments with the PhoneWave and the D-Mails proceed, Mayuri grows exponentially worried that they may be doing something wrong, but never attempts to stop Rintaro. As the number of members of the lab increases, and, in particular, due to the appearance of Kurisu Makise, Mayuri starts to think that Rintaro does not need her anymore, and starts worrying about her future.
In August 13, 2010, as the Future Gadget Lab is celebrating the completion of the Time Leap Machine, Mayuri is killed by Moeka Kiryu during the Rounder raid to the lab. This event leads Rintaro to travel back to the past to try and save her.
As Rintaro's time leaps continue, he is witness to Mayuri's death a multitude of times in a variety of ways, due to Attractor Field convergence. Despite his best efforts to reach the Beta Attractor Field, he unknowingly grows distant of Mayuri, which she notices. This, alongside Mayuri's recent dreams of her own deaths, makes her belief herself to be a burden to Rintaro.
Once Rintaro finally reaches the Beta Attractor Field after sacrificing the life of Kurisu, Mayuri is the one to embrace him as his mad scientist façade crumbles.
On August 21, 2010, as Rintaro goes back to the past alongside Suzuha Amane to save Kurisu's life, Mayuri stays behind with Itaru Hashida. After Rintaro returns, wanting to give up after having accidentally killed Kurisu himself, Mayuri is the one to return him to his senses.
Okabe must choose between saving Mayuri or Kurisu. Realizing that he harbors romantic feelings for Mayuri, Okabe and Kurisu decide to return to the Beta world line in which Kurisu's murder continues as planned, but Mayuri noticed that something strange was going on between Kurisu and Okabe so she decided to ask Okabe. After knowing about Okabe's journey to save her, about all people's happiness he sacrificed, and about Okabe's decisions, Mayuri cries and blamed herself, running to see Kurisu. When Mayuri encountered her, Kurisu was packing her things to go back to America. She runs and hugs her, saying she doesn't want Kurisu to disappear, only to hear that this was Kurisu's decision from the beginning and that she wants Mayuri to be happy; saying that Okabe loves her, she parts. After hacking into SERN's database with the IBN computer, 1% divergence is achieved. Okabe vows to remember his memories of Kurisu,and spends his time with Mayuri as lovers. On a date with Mayuri, she says she had a very important friend that she doesn't remember who and that sometimes, she hears a voice, a voice that tells her to 'find happiness'. Mayuri holds Okabe's hand (Doing 'Stardust Handshake') and wondering if that important friend is the reason she is with Okabe right now, saying she wants to say thanks.
Isolated Jamais Vu
After attempting to find a way to save Mayuri without sacrificing the life of Yukitaka Akiha, Rintaro ends up in an unknown worldline. After exploring Akihabara and trying to contact his friends, Rintaro finds out that only Faris remembers him.
Mayuri, who in this worldline still works at May Queen, does not have any recollection of Rintaro. However, since the first D-Mail has never been sent, her death has been avoided. Rintaro, although depressed over having lost his friends, recognizes that as a necessary exchange for Mayuri's life and accepts it.
Link of Corruption and Rebirth
As Rintaro refuses to sacrifice Luka Urushibara's feelings and going back to the worldline where she was born as a man, they both are left with no other option but accept Mayuri's inevitable death.
Several days after her funeral, Luka uses the Time-Leap Machine to go back to the day Mayuri died, with the intention of making her wish of seeing her wearing a cosplay a reality.
Recursive Mother Goose
After Kagari Shiina successfully recovers her memories after almost being hit by a truck while searching for the origin of a song she remembered, Mayuri discovers that she is her daughter from the future, and they proceed to live the several following months happily together.
However, as the time limit for the Time Machine's fuel approaches, Mayuri decides to go back to the past herself to convince Rintaro to save Kurisu. Kagari, not wanting to be separated from her mother, opposes, but as she discovers Mayuri's reasoning to do so, decides to go herself alongside Suzuha Amane. Their fate after going back to the past, however, is unknown.
After being brain-washed by Alexis Leskinen and capturing Rintaro Okabe against her will, Maho Hiyajo roams Akihabara, with no clear goal in mind. She then finds Mayuri Shiina, who is looking for Rintaro, and, out of her own frustration and desperation, tells her the truth about the death of Kurisu Makise and her own life. Mayuri then runs away.
As Rintaro wakes up after being rescued, he is informed by Itaru Hashida that both Mayuri and Suzuha have disappeared, and that the Time Machine has been destroyed.
Due to Attractor Field convergence, Mayuri is destined to die on August of 2010 in the Alpha Attractor Field. Even though Rintaro time leaps a multitude of times to avoid her death, not even his best efforts can trick fate. These are some of the ways Mayuri dies, as seen in the visual novel and the anime adaptation:
- Shot in the head.
- Hit by a car.
- Run over by a metro train.
- Hit by a policeman's bullet.
- Spontaneous cardiac arrest.
- Jellified after being sent to the past with SERN's incomplete time machine.
- Shot by a Rounder whilst in a taxi with Rintaro. (Anime)
- Stabbed by a Rounder whilst in a taxi with Rintaro. (Visual Novel)
In world lines where Okabe manages to avoid any and other means of death, as well as worldlines where she can't be killed by rounders because they are uninvolved, Mayuri only dies of heart attacks like the time when Kurisu accompanies her to ComiMa.
- "But isn't doing this bad? Mayushii doesn't want you to do bad things..." -Mayuri to Okabe.
- "We should work towards world peace. Like giving everyone an Upa cushion..." -Mayuri D-Mail wish.
- "Just look, we've made so many friends... There's Daru-kun, Chris-chan, Luka-chan, Suzu-san, Moeka-san, Feris-chan, Braun-san, Nae-chan and more! In the spring you seemed so lonely... But now you're fine. You don't need Mayushii to be your hostage anymore."
- "Finally... Mayushii was... useful... to Okarin." -Mayuri after protecting Okabe from being hit by a Rounder's car.
- "The whole time you and Chris-chan were hurting... While Mayushii was making costumes... like nothing was wrong... I feel so stupid! I didn't know anything! I need to see Chris-chan!" -Mayuri to Okabe after knowing what Okabe and Kurisu have been through.
- "Hum, I don't know who it was but Mayushii feels like she had a very important friend. And whenever I think about that important friend, my heart hurts, like hnng, you know? And sometimes, I hear a voice. That voice tells me to 'find happiness'. I wonder if that person is the reason of why Mayushii is with Okarin now... If I ever meet this person again, I want to tell them thanks." -Mayuri talking about Kurisu in her ending.
- "Tutturu~!" -Mayuri greeting someone. Also her catchphrase.
- Mayuri's voice was used as a user guide for the Phone Microwave. According to Rintaro, it made the Microwave sound silly.
- According to Okabe, his first kiss was with Mayuri in elementary school, though they were "just messing around".