|Name|| Eisuke Harukawa
|First Appearance|| Chapter 32
Eisuke Harukawa (春川 英輔 Harukawa Eisuke) is a one of the major characters in the HAL arc.
Harukawa is a master neurologist said to have mastered every field in only ten years. He has a calm composure and can be very dark and secretive, but he isn't really a bad person. Honjou Setsuna found him eccentric and odd but somewhat likable. Harukawa tends be act cocky around people he deems to have lower intellect, but becomes more open around people like Setsuna, Yako and Neuro. Harukawa created HAL by cloning his brain waves, forming an artificial intelligence in cyberspace which looked and thought identically to himself. He is also the one who came up with the Electronic Drug, and probably planned to showcase it along with HAL if he hadn't been killed.
Harukawa created HAL in order to recreate a patient of his, Honjou Setsuna, who had succumbed to an odd mental disease. He intended to recreate her with his memories of his time with her and the combined intelligence of himself and HAL's. He eventually realises his goals were impossible though, and even if it were he would have ceased from existence by the time Setsuna would be recreated. The password Harukawa made for HAL's protection is 1/1000000000000000000, a numeral which is known as Setsuna in Japanese.
Harukawa was a famous neurologist in the country and was acquainted with Dr. Honjou, a fellow intellect. Dr. Honjou introduced his daughter, Setsuna to Harukawa and asked him to help cure her of her mental disease. Harukawa complied and spent the followng months with her. He eventually grew attracted to her and became more devoted to healing her. The disease had taken over her in the end though, and Harukawa looked on in shame as he saw his patient rampaging through the days. Setsuna eventually died, and Harukawa swore to recreate her no matter what it would take.
Harukawa first appeared in the Onsen murder case, where he met Yako and Neuro. He had apparently created HAL by this time, as he was shown congratulating himself on the success of his project. His dark attitude made him the prime suspect later when Tsuyuki was killed. After Yako exposes David Rice as the real murderer, Harukawa, Yako and Neuro belittle David for his motives. David is put into custody, and Harukawa asks Yako and Neuro to volunteer as his test subjects when they are free, as he found their mental capabilities impressive.
Not long after the Hayasaka arc, Harukawa and HAL use the Electronic Drug on their two intended test subjects: Tetsuyuki Homura and an unnamed boxer. Both ran wild and were eventually caught by the authorities. Shortly after Neuro attempts to infiltrate HAL's territory, Harukawa finds out the Electronic Drug had been used on more than just the two intended people (in the anime, all the previous criminals, barring X and possibly Aya Asia were influenced by the drug). Harukawa realises the trouble his own creations had caused and panics, but before he is able to fix his mistakes HAL decides Harukawa is inferior to himself, and promptly kills him with Harukawa's own mind-controlled subordinates. Later, near the end of the series, Harukawa is shown to have created an advanced tracking program while he was alive within three days. It was used to locate Neuro after he had crashed into the Pacific Ocean.