Taowu incident at Seiin High School

The Taowu incident at Seiin High School was an attempt by the Taowu to achieve the Rosenthal family's desire to create the 'perfect golem', using the memories of death stored within the Misaka Network to transform itself. The event occurred at Seiin High School, which the Taowu's host Hirumi used to attend when she was still alive.

Rosenthal Family
The Rosenthal family is a line of necromancers who have spent over 400 years developing techniques of creating golems from corpses in order to create the perfect golem, one with a perfect soul and a perfect body - a god.

The method used by the Ronsethal family, devised by their ancestor Obed, involves placing an artificial soul into a corpse, allowing them to use a human brain and greatly increasing their intelligence as opposed to rock dolls only capable of carrying out simple commands. After Obed was exiled from his homeland and ended up in the east, his descendants continued to develop the technique with the 4th generation head Isaac incorporating the Taoist Hopping Zombie Spell into what would become the Rosenthal-style, and the 5th generation head Nathan, who developed artificial souls with greatly increased abilities.

Taowu
Among the artificial souls used by the Rosenthal family are four with greatly increased abilities which were created by 5th generation head Nathan; Taowu (檮杌), Taotie (饕餮), Hundun (混沌) and Qiong Qi (窮奇). These four, sometimes referred to as the Evil Spirits of the Numbers (ナンバーズの悪霊), are capable of producing superhuman strength when their charm is attached to a corpse.

The artificial soul, also referred to as a false soul (偽りの魄), is contained within a paper charm, which has several inscriptions on them, including a sephiroth which is a key part of the artificial soul. This charm is attached to a corpse in order to animate it, enhancing its capabilities in the process. The artificial souls, such as Taowu, tend to speak in a somewhat machine-like way, and have a number of programs, such as a self-diagnosis program, built into them.

The artificial souls are supposed to obey the orders of the head of the Rosenthal family, however Taowu is different. When Isaac was on his deathbed due to illness, his successor Nathan transferred his soul into the Taowu before it was damaged and lost to death. His will remained with the Taowu throughout subsequent generations, though knowledge of his presence appears to have been lost somewhere along the line. When the Taowu ceases reproduction of its host's personality and displays this will, the host's eyes change color and acquire slit pupils.

Memories of Death
After the Taowu was activated by Esther Rosenthal in an attempt to revive her friend Hishigata Hirumi, it was contacted by a self-proclaimed demon who conveyed a method with which it could achieve the Rosenthal family's desire. This method is derived from how the human soul is said to slowly evolve and reach Keter through the process of experiencing 10000 deaths. By converting the memories of death (死の記憶) into a special formula and adding it to the sephiroth constructing the artificial soul, engraving the proof of death into the soul 10000 times, their soul would also reach Keter. The memories of death are normally erased from the physical world at death, however the memories of 10031 deaths are present in Academy City, stored within the Misaka Network.

Posing as Hirumi, the Taowu presented this plan to her brother Hishigata Mikihiko in the guise of making Hirumi into a Level 6,  leading on from his research into discovering where esper abilities originated from within the body and reinforcing the body to enhance esper abilities, in order to create the perfect esper.

The exact identity of the entity who provided the method to the Taowu is currently unknown. When the Taowu first spoke of the entity, it produced a shriek which couldn't be understood by human ears, before referring to it as a self-proclaimed demon.

Transformation
After the memories of death were converted into a formula and integrated into the Taowu, it went about constructing the 'perfect body' in order to contain the 'perfect soul'. During the initial stage of the transformations, roots and cable-like appendages expanded across the school grounds, with a large mass in close proximity to the Taowu's host body, Hirumi. These cables could form copies of Hirumi. The cables converged in the middle of the school's courtyard and formed a giant mass with a slight resemblance to a flower.

In the anime, the body continued to grow from the ground upwards instead, while the tree remained until the growth had reached a certain point. A side-effect of the transformation was that color was reduced in the surrounding area.

According to Esther, even if this growing body was heavily damaged it would continue regenerate until the Taowu's charm was dealt with, such as through the use of Emperor Shun's Blade.

Background
Over 400 years before the present, having tested various methods of creating golems, the Rosenthal ancestor Obed, devised a method of inserting an artificial soul into a corpse to create a golem with greatly increased intelligence. The of his homeland wouldn't permit this and drove Obed away from his home as a heretic.

Ending up in the East, Obed and his successors would continue to develop their techniques, with the 4th generation head Isaac, incorporating the Hopping Zombie Spell and the 5th generation Nathan creating four artificial souls with increased abilities; Taowu, Taotie, Hundun and Qiongqi. Before Isaac died from disease, Nathan transferred his soul into the Taowu, imprinting it on its artificial soul. The Rosenthal-style would continue to develop over the subsequent 19 generations but their ultimate goal of creating the perfect golem continued to elude them. At some point along the line, knowledge of Isaac's presence within the Taowu was apparently lost.

In the present day, the 23th generation head Esther Rosenthal was apparently tricked into joining Hishigata's research team as a supervisor, enabling them to make considerable progress. During this time, she became friends with Hishigata's younger sister Hirumi who was attending Seiin High School.

After Taowu was activated for the 17th time when Esther attempted to resurrect Hirumi following her death, the Taowu was contacted by a self-proclaimed demon which conveyed a method with which it could achieve the Rosenthal family's desire. The Taowu, influenced by the will of Isaac, moved to carry out this method and accomplish their goal, posing as Hirumi to manipulate her brother Hishigata. As a result of losing her friend twice, Esther realized that they should not toy with death and abandoned the desire of the Rosenthal Family.

At some point along the line, the Taowu in Hirumi's body, Hishigata and the organization DA whom they were manipulating, started to make use of Seiin High School, specifically its Sixth Chemistry Building, as a base of operations. They also made use of the Rosenthal artificial souls in the Coffins. Meanwhile, Esther worked to stop them and the entity that was manipulating them to interfere with life and death.

Necromancer Arc
Through DA, Hishigata and the Taowu-possessed Hirumi attempted to acquire Last Order in order to access the Misaka Network and the memories of death. When they captured Misaka 10046 instead, they ordered DA to bring the Sister to Seiin's Sixth Chemistry Building, where DA's leaders intended to have the organization regroup after their clashes with several groups intending to eliminate them. After the DA forces transporting Misaka 10046 were defeated by Scavenger, Hishigata sent the Coffins to retrieve the Sister and bring her to him, with Accelerator in pursuit. At the same time, Anti-Skill had set up a barricade around Seiin High School, while fighting the remaining DA forces within the school grounds. While en route, Hishigata had the Coffin download the memories they required, and by the time Accelerator reached their hideout and rescued Misaka 10046, he had the memories of death at his disposal.

While Accelerator was preoccupied with the Coffins, Hishigata took the Taowu-possessed Hirumi away to download the formula derived from the memories of death into her. Esther attempted to stab Hirumi's body with Emperor Shun's Blade as the download was nearing completion but Hishigata took the blow just as it was completed. The remnants of Hirumi then came to the surface briefly, witnessing Esther with a bloody knife and her stabbed brother. As she screamed, the transformation started, with a mass of cables spreading throughout the school.

When the wounded Hishigata described what was happening and Esther tried to tell him the truth, he called Hirumi to tell her how she was wrong. Recognizing that Hishigata would die soon, the Taowu ceased replicating Hirumi's personality and spoke to Esther, revealing its manipulations in order to fulfill the Rosenthal family's desire and the method which was conveyed to it by the self-proclaimed demon. Esther pleaded with it to stop, trying to command it as the head of the Rosenthal family, however the Taowu refused to comply, revealing that it possessed the will of Isaac before proceeding with forming the 'perfect body'.

As the Taowu continued transforming its body, engulfing a large portion of the school as it did so, Esther resolved to stop it, together with Accelerator and the Huotou, possessing the corpse of Hitokawa Hasami. As the group were proceeding towards Hirumi's corpse and the Taowu's charm on the top of the growing body, Isaac grew impatient with its progress and attempted to speed up the growth by consuming members of DA which were nearby. However he ended up becoming overwhelmed by the consumed members' desires to enforce justice and lost control over the Taowu.

With time running out, Accelerator launched the group to their destination and with the help of the Huotou and Misaka 10046, Esther managed to pierce the Taowu's charm with Emperor Shun's Blade. With Isaac's will exorcised from the Taowu, Hirumi's corpse crumbled and the body began an explosive collapse - one which her dying brother estimated would level everything within 5 kilometers and destroy the city with its shockwave. His battery nearly spent, Accelerator focused all of his remaining calculation capabilities on his ability and managed to send the majority of the explosion into space.