Big Spider

Big Spider is a Skill-Out faction, first introduced in the Toaru Kagaku no Railgun anime. Originally founded by Kurozuma Wataru in The Strange, as a place for level zeroes to have a place to belong to in Academy City; Big Spider devolved into a violent gang that attacks espers, during Hebitani Tsuguo's reign as the leader. After the events of episode 16 of the anime, Big Spider has been dissolved as the result of the arrest of it's leaders.

Big Spider under Kurozuma Wataru
Wataru founded Big Spider a few years before the start of the series. During his time, his gang followed Wataru's example and knew where to draw the line. Big Spider during this time was a very popular and large organization, it included both young men and women level zeroes.

During a scuffle with another group in an artificial riverbank to protect a little boy, Konori Mii noticed the group and shortly joined them despite being a level 2 esper, and later donning a red leather jacket. She was later confronted by Wataru after he discovers that she was a level 2 esper, here he allows her to stay but tells her whether to stay or not. Some time after, Hebitani Tsuguo is kidnapped by a rival gang, they demanded Wataru to come alone to a specified meeting point if he wanted Tsuguo back, despite being a trap, Wataru agreed with their terms. Mii however protested his actions, citing that it was an obvious trap for him, Wataru however does not yield to her please, and tells her before leaving that this place (The Strange) may not be the best place for her to carve her name (referring to the fact that Mii tried write a love umbrella of her and Wataru previously on a rail).

Mii was correct in her assumptions that it was a trap, as it was reported that Wataru died in the building that was supposed to be the meeting point. However, Tsuguo is saved but is saddened by the apparent death of Wataru. In reality Wataru was still alive but needed medical attention. Shortly after the incident, Mii quits Big Spider and becomes a member of Judgment.

Big Spider under Hebitani Tsuguo
2 years before the introduction of Big Spider in the anime, Hebitani Tsuguo became the leader of Big Spider, using the name of Kurozuma Wataru as a cover. During this time Big Spider became more violent and had started arming themselves with weapons smuggled from the outside. In his stint as a leader, he turned his back on the ways of the former Big Spider and started attacking innocents. They later acquired Capacity Down from a mysterious benefactor and has made them bolder in attacking espers.

Dissolution of Big Spider

 * Main article: Big Spider Arc

The increased attacks of Big Spider, reached the attention of Judgment and Anti-Skill, along with the level 5 esper Misaka Mikoto; Kurozuma Wataru returns after a year and a half in detainment, determined to take down the now-corrupted group.

In a raid conducted by Anti-Skill on The Strange, Big Spider finally dissolves with the combined efforts of Mii, Wataru, Shirai Kuroko and Misaka Mikoto. Hebitani Tsuguo is heavily beaten and is later taken into custody alongside Kurozuma Wataru who requested his own arrest.

Clothing
During the time of Kurozuma Wataru, Big Spider members, both men and women sported distinctive black leather jackets. There are however exceptions in this clothing style, as exemplified by Konori Mii who wore a red leather jacket during her time with the group.

After the apparent death of Wataru, the distinctive clothing disappeared and Hebitani Tsuguo allowed group members to wear other clothing.

Transportation
Prior to the supposed death of Kurozuma Wataru, Big Spider members' primary transportation were motorcycles. During Tsuguo's reign as the leader of Big Spider, the motocycles have seemingly been replaced by vans, one which bears Big Spider's name.

Weapons and Technology
It is unknown whether or not Big Spider had weapons before Tsuguo became the leader, however, ever since Wataru's disappearance Big Spider has used various weapons such as guns and pipes, and also has access to explosives such as dynamite, Big Spider has also strucked deals with various illegal weapn suppliers from outside Academy City and have support from within the city. One of which was the developer of Capacity Down, which was given to Big Spider for experimental purposes and to gather data on the effects of Capacity Down on the espers.

Hideout
Big Spider used The Strange as their stronghold, where there is a high abundance of abandoned buildings for them to use as hideouts. The anime featured at least 3 different hideouts of Big Spider.

First Incarnation of Big Spider

 * Kurozuma Wataru - Original founder and leader. Currently detained by Anti-Skill.

Second Incarnation of Big Spider

 * Hebitain Tsuguo - Leader of Big Spider after the disappearance of Wataru. Currently detained by Anti-Skill under the charge of assault.

Members

 * Tamezou - Member of both incarnations. Currently detained by Anti-Skill.
 * Konori Mii - Member of the first incarnation, have since defected and is currently a member of Judgment.

Trivia

 * Konori Mii has a picture of her and other Big Spider members in her cellphone. She also has a bike that has a Big Spider logo marked on it.