Misaka Mikoto

Misaka Mikoto is the third ranked Level 5 esper in Academy City, and has been nicknamed Railgun due to her signature move. Kamijou Touma gave her the nickname "Bug Zapper", and whenever the two meet, he usually calls her that, even after his amnesia. She is considered the strongest Esper in all of Academy City.

Mikoto is the daughter of Misaka Tabigake and Misaka Misuzu. She entered Academy City in elementary age,[10] and distinguished herself as a child prodigy, initially starting out as a Level 1 and climbing her way up to a Level 5 esper. This made her a perfect candidate for the Sisters Project, which held the intent of cloning her for military use. Mikoto willingly gave a DNA sample to the researchers of the project after being told that it would help people who suffer from muscular dystrophy, a fatal disease.

She later enrolls in Tokiwadai Middle School at the age of 12, and soon becomes a Level 5. In her first year, she lost a 10,000 yen bill due to A Certain Vending Machine, probably explaining her propensity of kicking it. In one fateful event, she saved her future friend Shirai Kuroko from a robber by using her 'Railgun' ability. Kuroko eventually enrolled at Tokiwadai as well and gained great affection for Mikoto. Mikoto later became roommates with Kuroko in Room 208 - despite Kuroko being her junior - after Kuroko 'legally' removes Mikoto's previous roommate who was supposedly ill-natured towards Mikoto. Being a Level 5 esper as well as a student with consistently high grades, Mikoto is known as Tokiwadai's Ace.