Heaven Canceller

Often mentioned as "the Frog-Faced Doctor" by Tōma and many other people, he is an exceptionally-gifted and benevolent physician who can cure any illness and heal any injury, even if it is terminal. He is only unable to heal specific brain-related injuries, such as the Tōma's destroyed memories and Accelerator's computation ability; however, in the latter case, he was able to configure Accelerator to control his powers with support from the Misaka Network. While he may seen just like any other normal doctor, this medical genius also happens to be an acquaintance of the General Director of Academy City, Aleister Crowley as he manages the machines that extends Aleister life span while still supporting the foundation of the city itself.

It is also revealed Heaven Canceller was the one that came up with the idea of establishing Academy City, when he first met Aleister Crowley in a small England village many years ago when Aleister was on the verge of death from being hunted down by the entire Magic Side. He helped Aleister escape to Japan and helped Aleister to establish the city, but instead of taking on the role of the Founder he preferred to stay at a hospital where he can care for patients like he always had done.

The doctor has followed the Hippocratic Oath faithfully, even though he calls himself Accelerator's 'Senpai' and said he has lived through and seen much more darkness compared to Accelerator. He still wishes to help anyone no matter who they are and which side they come from, even after all that he has seen. After Vent's attack on Academy City on September 30th he warned Aleister to stop messing around with his patients, to which Aleister replied the only way for that to happen is to stop the machine that prolongs Aleister's life. However he could not do so, since even after all Aleister has done Aleister is still one of his patients.

He also is the creator of the "Dark Legacy", a tool discarded a long time ago probably during on his young age, which is now on Aleister's hands and used to keep Mugino Shizuri and Kakine Teitoku alive after the events of the Volume 15

.