Big Spider

Big Spider (ビッグスパイダー Biggusupaida) is an organization and is the titular main antagonist faction of the Big Spider Arc of Toaru Kagaku no Railgun. It's a criminal organization and is a faction alligned with Skill-Out and thus, is made up of Level 0 Espers who fight for a cause of giving Level 0s a place to belong but have since turned to attacking innocent civilians under the leadership of Tsuguo Hebitani.

Background
Big Spider was created one day in the past a few years prior to the series. The group was originally founded by Wataru Kurozuma where it was a very peaceful biker gang comprised of many young boys and girls who were all Level 0 Espers and was a very large and popular organization at the time. One day, a scuffle broke out between Big Spider and a rival gang where they managed to beat the gang back and a young kid was saved by them. This caught the attention of a young Mii Konori who, despite being a Level 2 Esper, became a member of the group and dawned a red lether jacket. Konori had a close relationship with Watary who kept her abilities hidden from the others and protected her. One day however, Tsuguo was kidnapped by a rival gang and Wataru went to save him but the building collapsed and he was supposedly killed. In response, Konori abandoned Big Spider and defected over to Judgment where she got a better more peaceful life.

Second Incarnation
After the death of Wataru, Tsuguo used Wataru's name as a false identity and managed to rebuild and reform Big Spider. Under his leadership, Big Spider turned into a violent organization and began attacking innocent civilians and harming espers with abilities which went against the ideals of the group's founding ideals. In an attempt to gain more power, Big Spider got involved in the black market and aquired both illegal weapons and the Capaticy Down from Therestina Kihara Lifeline.

Big Spider Arc
Two years later, Wataru has now returned and has betrayed his former organization. He is first seen where he saves Mitsuko Kongou from a small group of Big Spider members who are using the Capacity Down against her and Tsuguo orders Wataru to get taken down. Overtime, Mikoto Misaka and her friends get involved which eventually results in Mii Konori and her co-workers at the 177th Branch Office got involved and began to fight against Big Spider. At first, they are overrun but Wataru interviens and saves them and eventually, Anti-Skill arrives and arrests all of the members of Big Spider. Wataru turns himself in and has a short little talk with Mii before going off to jail. Following the battle, Big Spider has been dissolved as all of its members are incarcinated.

Leadership
Big Spider was originally led by Wataru and was a peaceful organization. Big Spider had been a biker gang and only engaged in short brief fights in the past until Wataru almost died and managed to survive. Since than, Tsuguo then took over Big Spider and turned the organization into a violent militant group that began attacking innocent civilians and engaging into illegal activities. This resulted in Wataru returning and began a plan to destroy his former group.

Activities
Big Spider was once a biker gang and its members were mearly simple folks looking for a good time back during its early days. Under its second incarnation however, it went under dramaitc new changes. Big Spider now acts as a rogue criminal organization that has been engaging in fights against espers by using the Capacity Down to attack and harm Level 1-4 espers and engaging in illegal activities like smuggling weapons.

Resources
Big Spider heavily relies on weapons since all of their members are level 0s and lack any abilities. Members typically carry weapons like metal pipes and other blunt objects along with firearms like pistols and such. Transpertation is made up of motorbikes and minivans and their bases are abandoned facilities. Capacity Down is Big Spider's overall trump card as it will disable espers' abilities and makes it easier to take them down. After it's destroyed however, Big Spider has all their members beaten and Anti-Skill and Judgment takes them in.

Notable Members

 * Wataru Kurozuma - Original Founder and Leader of the first incarnation (formerly)
 * Tsuguo Hebitani - Second and current acting Leader of the second incarnation
 * Tamezou - Member of both incarnations
 * Mii Konori - Member of first incarnation (defected to Judgment)
 * Numerous Unnamed Members

Trivia

 * Big Spider is named after Wataru's spider tattoo that its original founder had.
 * Konori has a picture of her and Big Spider members from the past on her phone.
 * Big Spider is made up of all Level 0s like all of Skill-Out however, Konori was able to join because of her abilities being hidden.