Mayuri Shiina

Mayuri Shiina (椎名まゆり, Shiina Mayuri), also called Mayushii, is Rintarō Okabe's childhood friend and companion. She works part-time at a maid cafe called May Queen Nyan-nyan as a costume maid and occasionally makes cosplay outfits. She is usually the one who financially supports Rintarou's "research" when food is needed.

Appearance
Mayuri is a girl with black hair and gray pupils. 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 leggings underneath her clothing.

When she attends to her work in May Queen Nyan-nyan, she wears a blonde wig tied into a long ponytail.

Personality
She possesses an extremely childish and naïve attitude for her age. This may have something to do with her inability to accept the death of her grandmother when she was young. Mayuri likes to give cute nicknames to familiar people, like Rintarou (Okarin), and refers to herself as Mayushii. She often misunderstands or misphrases information she overhears from Rintarou or Kurisu, though at certain times her responses can be quite helpful. Also, Mayuri does not question Daru's perverted comments and mannerisms, or is not in any way offended by them (though this is likely because she does not interpret them as such).

Despite being socially inept, she is also responsible for Rintarou's well-being, usually tending to his needs most of the time. She's also very attentive to details, often noticing things about people that others would miss. She figured out Suzuha Amane is Itaru Hashida's daughter through the details on the Time Machine and from Daru's daily habits, suggesting a degree of skills in observation and problem-solving.

Background
When Mayuri's grandmother died, she spent all her time in front of her grave; this constantly worried Rintarou. Mayuri was in that state for several days, until a very rainy day when she dropped her umbrella and started raising her hand to the sky. (Which according to Rintarou, was like she was being taken by her grandma) Rintarou hugged Mayuri and remembered a mad scientist show that they had watched, where the mad scientist takes a hostage. Rintarou imitated the scientist and declared Mayuri his hostage, so that nobody can take her from him. Crying very hardly, Mayuri smiles a little and say it cannot be helped.

Plot
To be added.

Mayuri's Ending
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 blame 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 tell 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.

True End
Okabe, realizing that Kurisu will need to "die" (false blood and taser, thus altering the timeline but making it so their paths do not cross) if he saves Mayuri, decides to sacrifice being with Kurisu for Mayuri's life. Kurisu decides to go along with the plan. Okabe has no choice but to send the D-Mail. Everything started again like in Episode 1, and no one has memories of Kurisu, but Okabe. After hacking into SERN's database with the IBN 5100, 1% divergence is achieved. Okabe vows to remember his memories of Kurisu, and spends his time with Daru and Mayuri. But later, when Suzuha Amane comes back with the time machine made by Itaru to the present timeline, Okabe accepts to go with her back to the past timeline where Kurisu was killed, and subsequently crosses into the “Steins Gate“ (1.048596) worldline by faking Kurisu's death for his old self to see. In that timeline, Okabe ends up meeting Kurisu by chance, as Kurisu wanted to thank him for saving her life and could remember the few incidents as dreams, and she could recall her love life with Okabe.

Death(s)
Before achieving 1% divergence, Mayuri dies in multiple ways during Rintarou's various attempts to save her, due to the events of the world lines in this same attractor field always converges into the event of her demise, though with different results each time:
 * Shot in the head by Moeka Kiryū
 * Ran over by a train
 * Hit by the Rounders car
 * Hit by a policeman's stray bullet
 * Spontaneous cardiac arrest
 * Gel-i-fied
 * Shot by a Rounder whilst in a taxi with Okabe

Quotes

 * "But isn't doing this bad? Mayushii don'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 much 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 sometime, 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.
 * "Tuturuuuu"

Trivia

 * Mayuri's voice was used as a user guide for the Phone Microwave. According to Rintarou, it made the Microwave sound silly.
 * She was the first person to discover the Microwave's "irregular" abilities when she accidentally froze her chicken while trying to thaw it. She also gave the gel-i-fied bananas the name "gelbana".
 * So far, the only ending of the visual novel in which Mayuri's death is definite is Ruka's ending, as she survived in Faris's ending, Kurisu's ending (same thing applies to the True end), her own ending and Suzuha's ending (implied to have been saved through the combined efforts of Rintarou and Suzuha).
 * Also, Mayuri dies of natural causes if Ruka's ending was achieved. This is the one of two instances in the plot where the cause of Mayuri's death was not an accident/murder, the other being when she goes to ComiMa on the 16th after Ruka's mail is reversed.


 * Mayuri, like all other characters, has blurry memories of what happened to her in the other world lines, though unlike them she only thinks of the memories as "bad dreams".
 * According to Okabe, his first kiss was with Mayuri in elementary school, though they were "just messing around."
 * In one of the (failed) attempts to save Mayuri, Rintarou sent her to the past. However, instead of arriving normally, she dies and her body was gel-ified. This scene was only briefly shown in the anime.
 * The gel-ified Mayuri still resembles her normal form a great deal, as the details on her outfit along with the color of her hair are still visible and her body is not distorted in any way, unlike SERN's experiments.
 * Lab Member 002. Second to the founder, already joined at the start of the main story. She joined because she wants to be with Okabe, as she is his hostage.