Born into the Senju Clan on the night of the terrorist attack by the Cabal, Harou was left an orphan as both his parents were killed in the heinous attack. Debris had fallen on his mother right after she gave birth, causing her to be impaled by the destroyed structures. Senju Rikuto, friend and colleague to the family found Harou being protected by his mother’s body who attempted to shield him from the destruction from the attack. Unfortunately, Harou was gravely injured even as an infant and due to the terrorist attack on the village, aid was not immediately available to be given to Harou which resulted in permanent damage to his vital organs and respiratory system. He would be incapable of becoming a normal functioning adult, much less a shinobi.
Most of his childhood was spent reading stories and novels of legendary shinobis and warriors who protected Sunagakure in the days of yore. Of all the legends and stories he learned of, none fascinated the young boy more than the Ranger Order. The strength and Spartan like lifestyle they lived, along with their history fighting against the Gods and monstrous beasts of yore fascinated him. He often fantasized that he himself would become a powerful Ranger who would rid the world of monsters such as Sandworms and atrocities like the Cabal so none would suffer the life he himself currently was cursed in.
He was Senju in name only, his injuries preventing him from walking without aid much less train to be a shinobi. His resentment towards the Cabal only continued to grow as he held them responsible for his parent’s death as well as taking away his future. As he was unable to train his broken body, he began learning as much as he could about Sunagakure and its history and trying to find as much information as possible on the Cabal. His civilian like status caused many limitations on what he could read into, frustrated that he remained unable to find the information he desired without being a shinobi himself.
On his eleventh birthday, Senju Rikuto who had been secretly searching for someone to aid the young Harou had heard of a prodigal Med-Nin known as Byakko Kyuji who could possibly aim the young aspiring boy. Upon contacting Kyuji, the young med-nin explained the severity of Harou’s injuries, explaining that this was as permanent as it could get. Disheartened the boy fell into depression before Kyuji offered an experimental procedure to possibly aid the boy. However, the procedure was experimental and dangerous though this did not deter Harou who dreamt of becoming a shinobi, becoming a Ranger, and exacting revenge on the group that ruined his life, the Cabal.
For the next year, Senju Harou underwent various surgeries and physical therapy in order to improve his body and functions again. However his organs were also extremely damaged, as a result Kyuji created an experimental drug that would theoretically allow his organs to function normally. The drug was known as Belladona. As the drug was experimental, it had unknown side effects at the time of conception.
Belladona was originally created by Kyuji to aid Harou’s organs to function properly and help him attain better function over is physical capabilities. The drugs however functioned in a way to enhance strength, speed, and agility as well, functioning similar to performance enhancing drugs. Despite its potency, Belladona was found to be addictive and toxic to the body. His body became instantly dependent on the drug, Harou requiring a controlled, continued amount of Belladona in order to stay alive, as it took over his body’s vital functions. Failure for him to regularly take Belladona results in withdrawal symptoms, including dizzy spells, nausea, palpitations, and migraines. Longer withdrawals include hemorrhages, convulsions, hypothermic, labored breathing, and irregularities in cardiopulmonary activity, and eventual heart failure with certain death.
As a result, Kyuji created a depressant/tranquilizer as an opposite to Belladona, effectively becoming a “Downer” and the original drug becoming the “Upper”.
Upper reacts as a stimulant, increasing physical capabilities of Harou far beyond what his broken body was originally capable of. It also allows him to use his body to its limits, allowing him to function normally as well as extraordinary if overdosed on. An overdose severely numbs the pain receptors but also run the risk of incurring further organ damage and a manic state.
Downers act as a depressant or tranquilizer, slowing senses and movement. If taken alongside the upper, it can help maintain the body’s stability. This basically counteracts the effects of the Upper, to avoid overdosing on the upper. When overdosed on Downer, it can cause loss of consciousness, risk of organ damage as it reverts Harou’s body back to its broken state, and extreme fatigue.
As a result, they are usually taken together to neutralize the effects of one another and their symptoms are generally only visible when taken alone. Because of Harou’s dependency on the drug, Kyuji manages Harou’s drug supply strictly and monitors his physical condition closely.
After the successful operations, therapy, and medical drug. Harou was capable of far more than he imagined physically. He instantly enrolled into the Academy and began readying his mind in body for the goals he had in mind. His dream of becoming a shinobi, his dream of becoming a Ranger, and his dream of becoming a proper Senju in the future and undergo the Joining. Everything was but a step however, his true goal was to hunt anything and everything deemed a danger to the village and its inhabitants. He was going to become a hunter of all.