Yakumi Hisako

Yakumi Hisako is a member of Academy City Board of Directors who specializes in the medical field. She is the head of the Agitate Halation Project as well as many medical related researches.

Appearance
She has profound influence in the medical field. Her real age is over 70; however, her bones and organs are healthier than even those of a teenager like Tsuchimikado Motoharu because of special anti-aging treatments she has been using.

Agitate Halation Arc

 * Main article:Agitate Halation Arc

She originally is seen talking to Rensa 28 and appears to be a "doctor." However, she is actually in a hospital that people do not go to because there are fake rumors that the facility is an anti-terrorism trap disguised as the location of a member of the board of directors. However, the hospital actually is the location of the member in question, Hisako herself.

After the hospital that Hisako works in suddenly had an attempted power-outage, Hisako sent Rensa 28 to go and investigate the source of the attempted attack on the hospital and to check the Critical Pathogen Specimen Freezer on basement floor 5. She believed this was the top-priority area to check on first.

Hisako first tries to jump into an elevator shaft when she sees Tsuchimikado Motoharu who threatens her and because he falsely believes that Kaizumi Tsugutoshi is the person in charge of the Agitate Halation Project. He asks her for information on how to contact Kumokawa Seria and find Tsugutoshi.

Hisako has a pink smartphone with the password 7071. She gives the phone to Tsuchimikado Motoharu and allows him to send a message to Seria. In the end, she was manipulating the entire situation the entire time because she is actually the person behind the Agitate Halation Project.

Man-Eating Cockroaches
Yakumi Hisako has hundreds or even thousands of special cockroaches under her control. By applying psychosurgery and destroying specific brain cells with a neutron beam, they are made to want to eat anything and everything. As these are giant cockroaches from forests and jungles that eat wood, it means that they can also tear through flesh and bone, so they are used as a deadly weapon. Also, because they have not been genetically modified, if any of them escape and reproduce, their offsprings will not have the same characteristics.

Cockroaches and termites have the same evolutionary roots, yet Hisako chooses to use roaches in order to affect people's minds. That is because even if a person battles these roaches, it will eventually lead to mental exhaustion (and might affect the Personal Reality of Espers as well) due to the fact most people are disgusted by roaches.

Hisako controls the roaches with special microscopic scent capsules that use artificial pollen. These are prepared by taking the plasmagene the roaches use to gain resistance to insecticide by familiarizing themselves with the chemical. With two varieties of capsules, one to have them gather and one to have them disperse, she created a monitoring device to control the entire swarm, thus preventing them from assaulting her.

AIM thought being
Using the Agitate Halation Project, Hisako managed to elevate herself to become an existence based on the AIM Dispersion Field of Espers affected by the project, similiar to Kazakiri Hyouka or Aiwass. This was achieved after her body had been devoured by her own cockroaches and her consciousness being transferred to the shading computer. In this form she has no physical body, yet she can still talk. As the shading computer can use any gas or liquid that can be controlled with fluid mechanics, her ultimate goal was to preserve her thought processes on the air across the entire world to be reborn as a being that far surpasses AIM thought beings.

After being destroyed by Kamijou's Touma Imagine Breaker, Hisako's existence as an AIM thought being was destroyed, yet she was revived in a back alley thanks to her taking insurance beforehand. Now, her existence was based on the 'scent' emitted by leftover man-eating cockroaches that she hid even from her allies. As she is no longer based on AIM Dispersion Fields, it is unclear if she could be called an AIM thought being, and is afterwards referred to as an information life form. By turning her thought to words, she stabilized her existence which in turn allowed her to control the roaches' chaotic movements. Even though she no longer had any physical body, when Fraulein Kreutune found her she managed to 'eat' her existence, eventually leaving very little of it intact. It can be presumed that her abilities and existence are severely limited due to this.