Birthday: 1 Feb
Height: 151 cm
Weight: 45 kg
Second year in Kasensou Private Prepatory Academy. Childhood friend of Rintarou's, and slow by nature. Speaks in a very wavy manner, and seems to always be smiling and having fun. She's quite the optimist. She has trouble understanding complicated theories, but doesn't mind as long as it's enjoyable. Doesn't like people arguing, and is depressed when things are unpleasant. Though she'd like to ease the situation in such cases, she's not really good at reading between the lines. She often went with her grandmother to see the stars on her grandmother's back. Because of that, she has a habit of reaching her arm out to the sky at times, which has led Rintarou to naming it the "Stardust Shakehand". She abruptly does this (even if she's talking with someone), which surprises everyone around her. (Source: naomi.thewafflehouse.net) Major Spoilers
She gets killed the first time by SERN rounders when they storm Okabe's lab because she wasn't deemed a necessary person in SERN's construction of the time machine.
Despite Okabe's repeated attempts to save her in the alpha world line, Mayuri dies repeatedly either by accident (falling down the stairs, getting hit by a train, etc) or on purpose (throwing herself in front of an incoming car to save Okabe). This leads Okabe and Kurisu to conclude that her death is inevitable in the alpha world line and causes Okabe to undo the D-mail of the lab members to get back to their original world line to stop their past selves from ever hacking into SERN, and thus, preventing anything from happening.