Mayuri Shiina

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 has always been a little bit different, though he never goes into any detail beyond this. Mayuri has a great fondness for cute things like Upas, 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 {{char}}.

She also has a moral compass and becomes anxious and unhappy whenever Okabe does something "bad", such as hacking into SERN's files, although she does not do much beyond chiding him for it. She often seems to forget about it after a while or when the conversation topic changes, and rarely holds grudges.

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. Kurisu Makise comments on this, stating that while everyone else was concerned with the PhoneWave (name subject to change), Mayuri continued to take matters to her heart. This is shown when she was the one who managed to figure out that Daru was Suzuha's father before anyone else. Mayuri also does not question Daru's perverted comments and mannerisms much, or is not in any way offended by them.

Despite her apparent ditziness, Mayuri is distinctly aware of the fact that she is the least intelligent member of her group and struggles with a feeling of uselessness. According to Suzuha, the Mayuri in the future would frequently comment on her own uselessness with a depressed expression. In Steins;Gate 0, upon learning the truth about why Okabe chose the Beta Attractor Field, she feels as though Kurisu had more of a right to live than her as she was much more useful.

Despite her quirkiness, she is also responsible for Okabe's well-being, usually tending to his needs in a mutual bout of gratitude. In Steins;Gate 0, Mayuri shows great concern for Okabe's well being after Kurisu's death. Near the end of the game, she confesses that she has more than deep platonic feelings, proclaiming her love for Okabe to be superior to Kurisu's, yet wanting him to be happy with Kurisu even if it meant her death..