The Bount were a special race created for an original story arc in the anime adaptation of the original work.
The reason Jun had not thought of them at first was that he had not particularly liked that part of the story. It was a tragic tale, and all Jun saw in the Bount was madness and destruction.
Jun did not like sheer madness and destruction, so he did not like Kariya Jin. Besides, as a leader, Kariya was far too negative.
From the very beginning, Kariya Jin's goal had not been the survival of the Bount. Though he was a Bount himself, he believed the Bount were sinful and ought to disappear. In the end, he led the Bount to their deaths in Soul Society.
The reason he became the Bount's leader was that the Soul Reaper who had led the research project behind the accident in Soul Society had wanted to save the Bount out of guilt. Kariya Jin was the first Bount she saved after coming to the World of the Living, and she also gave him some education and treasures.
Kariya Jin gained power as a result and helped other Bount gain power too. That was how he became their leader. There was no other reason.
Then that Soul Reaper, Aijima, was exiled after Soul Society discovered she had helped the Bount. As a result, she could not teach and guide Kariya Jin for long, nor could she save more Bount. She had no idea what kind of person Kariya Jin was, or what he would later become, ultimately leading to all the tragedies.
After saying so much, he still had not explained what had happened back then. Judging from the dates in the Journal, the accident had occurred nearly three hundred years before Jun transmigrated, some eight hundred to nine hundred years before the era of the original work. In other words, it had happened a little over a hundred years after the First Thousand-Year War.
The original work explained that the accident had resulted from research into immortal souls. There was nothing wrong with the research itself, because souls in Soul Society would die sooner or later too. Even after becoming Soul Reapers, they were unlikely to live for thousands of years unless they were as strong as Old Man Yamamoto or the bearded Ichibē Hyōsube of the Zero Division.
If someone among the nobles lacked talent, it was understandable for them to worry about the length of their life. Jun guessed that a considerable number of those seeking longevity had been members of Central 46 at the time.
If Central 46 had not wanted to do it, what standing did a few nobles have to make the Seireitei research institute set up a secret team solely to conduct covert experiments? They had even been able to use Soul Reapers as test subjects. In the end, the experiment failed, blowing up a tenth of the Seireitei and causing Central 46 great embarrassment.
In the explosion, some of the special Reishi produced by the research passed through the Dangai and scattered across the World of the Living, merging with the bodies of certain humans. This special Reishi activated the power of their souls, but because it was special Reishi, it also transformed their bodies.
These humans became Bount. They neither aged nor died and could not reproduce. At the same time, their Reishi Quality had fully developed, allowing them to absorb Spiritual Power. But because they were restricted by their physical bodies and had not acquired it through training like the Quincy, they could not control it.
That turned them into individual light bulbs of Spiritual Power. Whether Soul Reapers or Hollows, anyone could find them with ease. In these circumstances, Soul Reapers assigned by Central 46 began slaughtering the Bount, while Hollows regarded them as the finest food.
Of course, ordinary Hollows would still have a hard time eating a Bount. Although the Bount could not control their Spiritual Power, a Hollow could easily get itself killed by their innate strength. But for some Evil Spirit Hollows, eating a Bount was a tremendous boost, and it was not impossible for one to evolve into a Gillian after doing so.
"So are there still Bount around now?"
"There should be. A lot of Bount went into hiding. After all, our assignments in the World of the Living are to watch over populated areas and guide departed souls. Remote wilderness and places like that aren't under our jurisdiction."
The young couple were still strolling along when another question occurred to Isuzu. "Wait a minute, Jun. If what you're saying is true, the Bount all look human. Soul Reapers don't normally kill humans, so didn't anyone question Central 46 when they issued those orders?"
"Why do you think they're called soul hunters?"
"Yeah! Why?"
"They're humans whose Reishi Quality has fully developed. In essence, they're no different from us Soul Reapers. Do we need to eat food from the World of the Living?"
"Ah! Their food is Reishi! They need to exchange Reishi too!"
Jun nodded. "Exactly. They need to exchange Reishi, but the Reishi in the World of the Living is different from that in Soul Society. It's extremely stable, and unless someone has tremendous strength, they can't manipulate it at all, let alone complete a Reishi exchange. So what would a Bount do to get food?"
Isuzu shuddered all over. "You mean they eat people?"
"They don't go quite that far, but they do eat souls. Some powerful Bount can eat Hollows too, but Hollows aren't as tasty as souls. Besides, ordinary souls don't have much power and won't resist, so there's no danger at all."
"Then aren't they eating their own kind?"
"Their own kind? From the moment they stopped aging and dying, do you think any human would acknowledge them as one of their own?"
Isuzu felt terribly sorry for them. "So they're not human, not Soul Reapers, and certainly not Hollows. Wow! Nobody acknowledges them, and isn't eating souls taking work away from the Soul Reapers?"
"You finally understand the crux of the problem."
"Whew..." Isuzu drew a long breath. "That's why Soul Reapers would naturally kill these Bount! Oh, heavens! Could it be that Central 46..."
"That's exactly what it is. All Central 46 had to say was that a special kind of monster called a Bount had appeared among humans and that it ate souls. That was enough."
"How pitiful..."
"Yes, truly pitiful."
Yet Isuzu did not question Central 46.
The young couple's life in the World of the Living had turned into wilderness survival. They headed wherever there were fewer people and climbed into every cave they saw. Sometimes they even foolishly explored places that were clearly inaccessible to humans, then came out and teased each other for being silly.
Though the Bount they were looking for had lived tragic lives, that did not affect the couple's happy life. There would be plenty of time to worry after they found them.
The World of the Living was in Japan's Sengoku period. Though it had not yet descended into the chaos that followed Nobunaga's rise, it was not much better. Corpses of people who had died in all sorts of ways littered the roads, and wild beasts roamed the mountains and fields.
"The World of the Living really isn't a nice place."
"Mm. Compared to the World of the Living right now, Soul Society really is Heaven."
"Hm? Jun, do you think the World of the Living will be wonderful in the future?"
"I don't know, but the World of the Living keeps developing, while Soul Society stands still."
"Is change really good?"
"In my view, only change brings vitality. If people don't change, why live? Birth, growth, old age—which of those isn't change? And if you don't want to change, can you control that change?"
"Mmm... You're always saying things that make my head hurt, Jun."
"Haha. Hm?"
"What is it!? Did you find something?"
"I think so."
The young couple were at the southernmost tip of Kyushu. Farther south lay a great many small islands. Of course, these were not the islands around Okinawa; during Japan's Sengoku period, Okinawa was still the Ryukyu Kingdom, a tributary state of the Ming dynasty.
Some of these islands served as stopping points for ships, while others were uninhabited. Those deserted islands were actually ideal hiding places for Bount. That was why Jun had come here, and now he really had found something.
"Let's go."
Using Shunpo, the couple quickly reached a deserted island a hundred kilometers away. This was the maximum range of Jun's Kakushitsuijaku at present, and after they arrived on the island...
"There are so many. There are some on the nearby islands too."
Even Isuzu could sense them, which showed the biggest problem: Bount really were easy to find. They had no ability to conceal themselves at all.
The couple walked until they were directly above the nearest presence. The person was underground. Jun pressed his palm to the ground and released a surge of Spiritual Power. The Reishi activated the stable Reishi throughout the island, leaving it highly active for a while. At the same time, Jun received a three-dimensional map of the entire island's terrain.
"Follow me."
"Wow! Darling, your Kidō is amazing! You created this Kidō yourself, didn't you?"
"Mm."
"Hee-hee, that's incredible!"
The two made their way around to the western side of the island. It was completely submerged now, but there was a large cavern beneath it. Many island reefs like this had all sorts of caves.
The couple were Soul Reapers, so they would not die from lack of breath if they jumped into the sea. They would, however, be squeezed by the seawater. The Reishi in matter in the World of the Living was especially stable and dense, so it was actually very uncomfortable for Soul Reapers to pass through matter there.
"Wow... Being in the sea is so uncomfortable."
Jun did not comfort his wife, because his eyes had met the other person's. It was a Bount, a desperate Bount.
"I ran all the way here, and you still won't leave me alone?"
"Jun, why is he talking so strangely?"
Jun looked around. The place showed signs of long-term habitation. The Bount had also suffered a broken arm and a broken leg, both of which had mended in a bizarre fashion, obviously without medical treatment. Bount merely neither aged nor died; they were not indestructible.
"He's probably lived alone for so long that he's almost forgotten how to speak. Humans aren't Soul Reapers. Their physical bodies make them lose a lot of things."
"I see... Jun, what should we do?"
"You—"
Jun had only just begun speaking to the Bount when he saw him limp away. The sea had sealed off the place, but the Bount still jumped into it without hesitation, because Bount could not die.
Of course, Jun would not let him escape. He caught him and brought him back with a Bakudō.
"What's your name?"
"My name is Koinu."
"Huh? What kind of name is that? What's your surname?"
"Only noble lords have surnames."
"That's how it is in the World of the Living. Do you want something to eat?"
When the Bount heard Jun's question, he broke down at once. The Bount was not afraid of death, and he was a man of little experience or education who understood nothing. As soon as Jun asked, he told him everything.
The Bount had discovered a long time ago that he neither aged nor died. Then his lord found out, and a group of samurai captured him. They tried cutting him open and digging out his heart and liver, but Bount could not die.
However, once they went too far, even a Bount could not recover on his own. The lord thought he was dead and had him thrown out. Then he encountered a Hollow, which began eating pieces of him.
He had been cut to pieces, so though he was afraid, he could do nothing. He wanted to fight back and desperately wanted to live. Then, suddenly, a burst of power erupted. His whole body recovered, and the Hollow died. Terrified, he ran away.
He wandered from place to place for more than ten years and suffered a great deal. He was even forced by a lord into an Undying Army made up entirely of Bount, and he fought in battles.
Unfortunately, the leader of the Undying Army killed the lord. Just as the leader was about to become the new lord, Soul Reapers appeared and killed most of the Undying Army. Only a few escaped, and he was one of them.
Then he fled to an island, where he lived for over three hundred years. He no longer even knew what time it was. Only when he was unbearably hungry would he leave the island for a human settlement, live in the wild, and wait for humans or livestock to die. Yes, he could eat the souls of animals too, though they were not as tasty as human souls.
He eked out a living like that and had been discovered before. His arm and leg had both been broken by someone, and he did not know how to set them himself. They slowly grew back together later. He had wanted to heal his whole body as he had back then, but he could not bring out that power no matter what he did.
"Do you want that power?"
"What did you say!?"
Jun was like a devil, tempting an old farmer who understood nothing. It was a familiar fairy-tale trope, and precisely because it was a trope, it worked exceptionally well.