The Morality Manipulation Machine (道徳操作機 Doutoku Sousa Ki in Japanese) is a Demon Tool designed by Eibon and created by Arachnophobia, based on a blueprint from the Book of Eibon. The prototype of the machine is destroyed by Sid Barrett and Mira Naigus. However, Arachnophobia soon created a new iteration of the machine, which was used to brainwash Kim Diehl and Jacqueline O'Lantern Dupré. After the invasion of Baba Yaga Castle, the Demon Tool was seized by DWMA and, along with the blueprints, were locked in DWMA's Secret Vault.
The Moral Manipulation Machine consists of a chair fitted with shackles to restrain subjects. Hanging above the chair is a red helmet with yellow spikes to be placed onto the subject's head to inflict brainwashing. The Machine also seems to have a monitor with a light bulb above it. The chair has a few levers on its side with masses of pipes and wires connecting the Machine to various pieces of machinery. (Interestingly, some of the Machine's wires are connected to what looks like a Golem, known as Type. 0000.)
|“||Insanity cannot exist in a moral vacuum. Some morals must remain in order to give shape to the madness. That is where our Moral Manipulation Machine comes in. It will alter people's sense of morality without obliterating it. Even a slight deterioration will give rise to the madness we seek.||”|
—Mosquito, Episode 28
Through the use of magic, the Morality Manipulation Machine, as its name implies, allows Arachnophobia to lower a subject's morality, subjecting that person to madness. As Mosquito claims, lowering a person's morality even by the slightest will increase the growth of insanity in the subject, which fulfills Arachne's goal of increasing madness in the world.
The Morality Manipulation Machine is probably used on members of Arachnophobia who may suffer guilt or feel as if they are doing wrong in following Arachne's orders, which is why Mosquito uses it on Kim Diehl and Jacqueline O'Lantern Dupré. The effects are quite prominent in the subject, as their personality changes completely to a more evil, malicious and sadistic one.
However, the Machine can also raise subject's morality, as Ox Ford and Harvar D. Éclair did to undo Arachnophobia's brainwashing upon Jacqueline O'Lantern Dupré. So far the Morality Manipulation Machine has not been used to convert a "naturally" evil person to good. Furthermore, although the effects of the Morality Manipulation Machine are strong, there is evidence of people managing to return to their normal state without the use of the machine, as Ox manages to remove the Machine's effect upon Kim by demonstrating his concern for her.
The blueprint fragment of the Book of Eibon somehow fell into Arachne's hands, perhaps being the same blueprints of Eibon which Arachne took with her when she escaped Lost Island 800 years ago.
After the Kishin's revival produced enough madness to allow Arachne to revive herself, Arachnophobia soon began developing the demon tool.
Part in the Story
Led by Mosquito, members of Arachnophobia create a research laboratory on an Island Nation to the East where they may develop a prototype of the Morality Manipulation Machine. However, as this facility is within her jurisdiction of East Asia, Azusa Yumi spots the research facility, notifying Sid Barrett and Mira Naigus so they may infiltrate the facility, locate the Demon Tool, recover its blueprints, and destroy the Machine using explosives.
Sid and Mira accomplish their mission exactly, but thanks in large part to the unexpected arrival of Black☆Star and Tsubaki Nakatsukasa, who perform a frontal assault on the laboratory to avenge Maka Albarn, who had been paralyzed by Arachnophobia's leader.
Sid and Mira returned to the Death Room to report to Death their destruction of the Morality Manipulation Machine and their recovery of its blueprints. Death ordered that the blueprints be locked in the DWMA's Secret Vault and that its location be kept confidential from all other parties. Despite Mira's disagreement based on how dangerous such a demon tool could be, Sid followed Death's orders.
Eventually, Arachnophobia had completed a new iteration of the Morality Manipulation Machine, having likely retained copies of Eibon's blueprints.
After Kim Diehl and Jacqueline O'Lantern Dupré defect from the DWMA based on Kim being outed as a witch, Mosquito entices the two to join Arachnophobia, on the pretense that they would be protected. Instead, Mosquito restrains the two students as the first test subjects for this Machine, lowering their morality and making them dedicated members of Arachnophobia.
Thanks to information provided by Medusa, the DWMA learns the location of Baba Yaga Castle. Medusa leads DWMA students, including Ox Ford, Harvar D. Éclair, Kilik Rung, Fire and Thunder, to the castle, instructing the students to walk to Tower Number 2 to destroy the Lock to the Spider Queen's Room. On their path, the students pass two Arachnophobia scientists discussing how the Morality Manipulation Machine is a success.
But Ox can sense the presence of Kim Diehl's soul inside the castle. With Kilik's urging, Ox and Harvar leave Kilik and Fire and Thunder to complete the mission while they search for Kim. In one smokey room, where Arachnophobia members are in a haze, Ox and Harvar run into Kim and Jacqueline, both under the influence of the Morality Manipulation Machine and, with these new murderous personalities, ready to attack Ox and Harvar.
As Kim prepares to kill Ox, Harvar protects his meister, fatally stabbing Kim—until he discovers her wound healed, thanks to Kim's healing properties as a witch. While Kim claims she can never return to the DWMA because people do not change, Ox proves her wrong, willing to give up his distinctive haircut if it would mean that Kim could put her faith in him and let him be her "home." Overwhelmed by Ox's devotion, Kim breaks down crying, the effects of the Morality Manipulation Machine dissipating. Jacqueline, however, is still under the machine's influence. As Jacqueline attempts to attack Ox, Harvar knocks her unconscious, taking her to the Morality Manipulation Machine, which returns her morality to its previous status.
Shinigami meets with Kim, Jacqueline, Tsubaki Nakatsukasa, and Sid Barrett, along with Angela Leon, retrieved by DWMA after the death of Mifune and her rescue from Arachnophobia. Sid and the students attempt to convince Death to spare the lives of the witches Kim and Angela. Kim argues that she may be able to suppress Angela's destructive witch instinct by exposing her to her Regeneration Magic, while Jacqueline suggests using the Morality Manipulation Machine, although she admits that she does not like putting forward this idea. The manga presents no evidence that DWMA ever used the Morality Manipulation Machine on Angela.