Mikagami Nagisa

Mikagami Nagisa (水鏡 凪紗) is a student of Tokiwadai Middle School who appears in Toaru Kagaku no Railgun. She was the leader of one of Tokiwadai's three great cliques; one year before the main story.

Appearance
Mikagami has freckles, green eyes and blonde hair, tied into a shoulder length braided ponytail with a blue ribbon. She wears the Tokiwadai Middle School uniform. She also wears a flexible sports bra and bike shorts under her uniform, which can withstand a drastic expansion of her body from her ability that would damage or destroy her uniform.

Background
In her years before middle school, Mikagami was continually approached by people who sought help from her ability, to the extent that most of her free time was taken up by it. In an effort to change this, when she entered Tokiwadai, she formed a clique and made it a rule that she would only use her ability for others as a reward, in an effort to minimize people approaching her. However, she underestimated how many people cared about their appearance and were willing to join, as well as the effort they would put in to get results, to the extent that the Mikagami Clique overtook the Hasekura Clique to briefly become Tokiwadai's number one clique before being overtaken by the Sha Clique.

At some point in the past, Kadosaka Rina and Sukezawa Sena did Mikagami's hair up in her current ribbon.

At the start of Misaka Mikoto and Shokuhou Misaki's first year at Tokiwadai Middle School, Mikagami was in her third year and leader of one of Tokiwadai's 'big three' cliques. The Mikagami Clique was apparently made up of students who were mostly drawn to her oil control ability and sought her to fulfill their own desires (such as manipulating fat in their body to enhance their bust or slim them down), with Mikagami only doing this for those who contributed the most to her clique. The clique was in second place and of the three, was said to be working the hardest to get results.

She is the youngest of five sisters and told her family that she can only control her own fat to keep her sisters from using her.

First Year Arc
Mikagami first encountered Mikoto in early May, just after the Level 5 had first met Sha Danshan. As Mikoto was introducing herself to Sha, Mikagami and Hasekura Reiri appeared from separate directions, with Mikoto between the three main clique leaders. After a brief exchange between the rivals, Hasekura dragged Mikoto off for a contest.

Around the time tensions were rising between the Mikagami and Hasekura cliques, with several skirmishes having occurred, Sukezawa and Kadosaka were with Mikagami, bringing up and offering sweets. As Mikagami was considering apologizing to the other clique to settle things, the two rejected that course of action as it would be the same as saying they were at fault for the initial incident, both vowing to protect her before asking for a few favors with her ability, though Mikagami had already started to leave. The two accompanied Mikagami, seemingly oblivious to her worries and internal dismay at how things had turned out.

Not long afterwards, as the three were walking together, they were attacked by Yasutoba Suika, who sought to crush the Mikagami clique's leader. After briefly getting away from the assailant, Mikagami urged the two to go a different way to her as she was the target, and ended up shouting to them as they refused, venting her feelings regarding her ability and the circumstances it had caused. Mikagami left hoping they would get to safety, but the two instead stayed behind to stop Yasutoba, to make up for the stress they and others had been putting Mikagami under.

Mikagami ultimately returned to defend the two after they were defeated and about to be struck after defying Yasutoba's demand to call for Mikagami. Using her ability to quickly shift her body shape and weight, Mikagami began pushing Yasutoba back. Yasutoba attempted to rattle Mikagami with comments regarding her clique, silencing the two when they tried to speak, but Mikagami was not rattled and after turning it back on Yasutoba, she proceeded to finish her off with a body slam.

After Hasekura returned and gathered electronic evidence with Mikoto's aid that suggested that the accused in the unseen attacks were not responsible, Mikagami agreed to a truce in the light of a potential external culprit. Although members of her clique objected to it, Mikagami was able to quieten them with her words (and the promise of using her ability for everyone if this led to the culprit being caught).

When the Mikagami and Sha cliques reinforced the Hasekura clique in a raid on the headquarters of Montgolfier, the culprit behind the attacks that instigated and aggravated the clique conflict, Mikagami was involved in the resulting battle with Montgolfier's operatives and their prototype weapons.

Abilities
Mikagami is a Level 3 esper and her esper ability is Oil Direction, which allows her to manipulate a target's oil content. This includes the manipulation of fat within a human body (e.g. for purposes such as bust enhancement or slimming), which she does for those who have contributed the most to her clique.

Mikagami is capable of fattening and slimming her body immediately, the former being used to resist attacks and increase the weight of her own attacks,  and the latter being used for speed and mobility or to slip out of bindings when ensnared in her fat form.