Hell-Hunter Program

"We Are Hell-Hunters, Humanity's Ascension and Demons' Destruction. -The Hell-Hunter Slogan
The Hell-Hunter Program is a project made by Dr. Greeves, funded by The Gentleman, in which live humans are imbued with Demonic essence, enhancing their capabilities.
== Origins ==
In 1960, the Gentleman had acknowledged the fact that he needed trained, militarized Demon-Hunters to not only retrieve specimens for his Research Division to examine, but also submit reports and bring in data that would bring him ever closer to unlocking the secret of Demons. By that time he was already researching a way to advance his lifespan drastically so that he would not die before his work was complete. 
When Kennedy took office, the Gentleman managed to attain a live specimen of a Demon from some Gypsies in Russia. Dr. Greeves, a young scientist at the time, was fascinated with the creature. He managed to attain some of its "essence", as he called it, and keep it stored in heated culture fluids. The mixture stabilized the essence, as he would learn, and allow it to be transferred into a human body, specifically the blood stream. The Demonic essence merged with the red blood cells of the human and spread through their body, "tainting" everything they came in contact with and enhancing them ten fold. Injured subjects would feel little pain, even when having an ankle broken. A line of subjects were capable of running on treadmills for 2 hours without sweating or showing signs of wear. When Greeves pitted an acclaimed "street boxer" who had been subject to the essence against a machine that rated the strength of a punch, the man managed to reach the highest level the machine could offer. 
These results astounded and amazed both Greeves and the Gentleman. However, one thing that shocked them was that the subjects all died within days or weeks, literally rotting to death in their beds. Greeves noted the smaller the doses of essence granted, the higher the survival rate. The Gentleman then had the doctor spend a few weeks preparing the essence while he rounded up some trust worthy soldiers to volunteer for the project. His own brother was the first to volunteer when the idea was presented to him. The next candidate was a skilled whipmaster Mercenary serving in the Gentleman's Military Division as a Shocktrooper, but he turned the offer down after his cybernetic enhancements were implanted. The replacement was a loyal commanding officer in the same Division as the whipmaster, who readily agreed to the offer when it was first set on the table. The third candidate was the longest to find and the most sought after by people under the Gentleman, who tried in vain to prove their combat skills worthy of receiving upgrades. At the time, the Gentleman's brother, Abraham, who was a member of the Black Rose Company, offered his pupil, Chapel, but the Gentleman had already found a third subject: a woman named Yuka Yatsumaru who was greatly skilled in the arts of the Katana, despite being blind. 
With the three volunteers prepared to receive the essence, the Gentleman dubbed them "Hell-Hunters"; a privately funded, supernatural-military task force. With the small dosage of essence in their bodies, the three became the Gentleman's most skilled fighters. Abraham, after a few weeks, resigned his commission in the Black Rose Company to become a full-time Hell-Hunter. The second volunteer, David Newman, became a guinea pig for Dr. Greeves' tests. Yuka was cured of her blindness but still practiced closed-eye swordsmanship with great skill. So the first generation of Hell-Hunters were born.
== Second Generation ==
Though Yuka remained active, Abraham retired and David became a test subject of Greeves' experiments. This, coupled with a need for more military might and activity, pressed the Gentleman to create more Hell-Hunters. Yuka offered to train the new candidates, who consisted of seven specially-trained soldiers in one of the Gentleman's private armies. Yuka developed a specialized test for the ending course of her Hell-Hunter training; the Yatsumaru Simulation. She dubbed it thus due to her desire to have children but inability to do so, so in a symbolic way of adoption-through-skill, she could gain some. 
One of these second-generation Hell-Hunters was Akihiro Yatsumaru, a tactically-elite commander who has a love of old art and music. However, after a mission went wrong and he defied the Gentleman's orders, he went rogue and took some of his followers and comrades with him to form his own Demon-killing organization. He was the first and only Hell-Hunter to pass the Yatsumaru Training Simulation.