Ishihara Ryuhei was born no one special. He grew up outside of Osaka in a village that was mostly farmland. He had a mundane life. He went to school, left home to go to university, and eventually became a teacher himself. He married and even had two children. It was during this time that the flame of nationalism began to rise within the Japanese spirit once again. Imperialistic attitudes prevailed, and Japan entered into the stage of the second World War. Like so many other young men, Ryuhei was swept up in the tide, moved to tears for his country, and signed on the dotted line to join the effort to reclaim Japan's lost independence and greatness.
Ryuhei wasn't the greatest, nor the worst soldier. He was fairly average, with nothing drawing attention to him. He was, however, dedicated and passionate. He bought in fully to the idea of Bushido, as it was presented in propaganda at that time. He wanted to give his life for his country. Up until the moment it was actually requested of him.
Iwo Jima. It was a losing battle from the start. There was no possible way for America not to take the island. High ranking officers knew it. The Americans knew it. The rank and file soldiers knew it. Ryuhei knew it. To him, it seemed almost a betrayal. He, along with so many others, were sent here to this island to die. Not to defend Japan from the barbaric Americans, but just to die to make a point. Some thought it beautiful. They claimed it was an expression of Japan's spirit, the spirit of Bushido. Ryuhei, not so much. Still, he would do his duty.
For over a month, the nightmare went on. American mortar shells became a lullaby for the Japanese soldiers bunked down inside the network of caverns that crisscrossed the island. Defending passages from American flamethrowers was becoming a true art in and of itself. Supplies were hard to come by, and raids on Allied encampments became necessary to survive. Some of Ryuhei's peers had already begun to consider slicing their bellies to just end it. Still, Ryuhei was determined not to die in this place, no matter what his country asked of him.
It was during one of the final nights of the battle that the world cracked open for Ryuhei to vomit forth an incomprehensible truth. As Ryuhei and a few others were traversing the caverns in order to sneak up on an American outpost for a supply raid, they came across a section of tunnel that had collapsed. Dislodged from the wall was a mummified corpse. When one of Ryuhei's squadmates went to investigate it, the withered, skeletal figure sprung to life and began to devour the hapless victim.
It was a nightmare made manifest. They opened fire on the creature, but their bullets seemed to have no effect on the monster. Their swords were merely knocked away with bare claws, as if they were children's toys. This thing... this Gaki... was relentless. Ryuhei and his men fled. Though they were separated, it was clear that the creature was hunting them down, one by one. Ryuhei managed to make it through the night. In the light of the day, he felt that he was no longer being hunted.
This went on for several nights. Every night, more and more people vanished, with the rumors of the Hungry Ghost spreading from one group to the next. Even the Americans, it seemed, were not safe from the creature, as it was whispered that they, too, were reporting soldiers vanishing in the middle of the night. After loosing so many of his friends to this hopeless battle, and now, to this monstrous being, Ryuhei could no longer tolerate it. He went AWOL, sneaking deeper into the caverns, in order to hunt down the beast and put an end to it. The hunter would become the hunted.
The battle for Iwo Jima ended, but Ryuhei's mission did not. For several months, he and the Gaki played a game of cat and mouse with one another. They both preyed on those who were left, holding out in the caves. They both raided the Allied camps under the cover of night, killing Americans for sustenance and survival. Ryuhei was always one, maybe two steps behind the creature. On some nights, he would even catch a glimpse of it. Every time, it seemed more human and less of a monster. Every time, it beckoned him on, as if taunting him to end it's unholy existence.
But all games come to an end, eventually. Ryuhei was caught by the Americans while trying to get food. As he was being taken prisoner, the Gaki appeared from nowhere. The marines didn't stand a chance against the inhuman speed of the undead thing. In the end, they were torn to shreds, and only Ryuhei and his tormentor remained standing.
The Gaki introduced itself. He explained that he was the heir to ancient gods, with a sacred mission. He had been asleep for ages, but violence of the battle had awoken him. He had seen Ryuhei's cleverness, and saw potential in him. That night, the Gaki devoured Ryuhei's blood, and replaced it with his own god-cursed ichor. From that moment on, Ryuhei would carry on with this legacy, in the cult of Orochi.
Since then, Ryuhei has studied under his mentor diligently. The cult has connections to all walks of life within Japan, and is seeking to expand it's interests abroad, into the US and abroad. Ryuhei is now on his own, sent to America to help establish the cult's presence in the area, though his purpose is a mystery, even to him.