"Actually..."
Faced with the choice before him, Issei wanted nothing more than to slip away with Genjutsu and avoid the whole mess. But something told him he shouldn't. Rias Gremory was the upright type—no pretense, no scheming, no lies. Even though there were easier ways to coax someone as reckless and underdeveloped in judgment as himself into her [Peerage], Rias had come at him head-on. Issei wanted to trust her, and he wanted her trust in return. Well, that was the excuse. Really, he was just being dragged around by lust and trying to make things go well for himself.
"It'll be faster to show you than explain. Flying Thunder God Technique!"
He placed a hand on Rias's shoulder, formed a seal with one hand, and the two of them vanished together in an instant. When they arrived, they were in the town park. Devils could travel with magic circles too, but seeing a human pull off something like this still startled her a little.
"This is..."
"It's called ninjutsu. Power that only humans can obtain, because only humans can wield it."
Of course, that was a lie. He was only saying it because it sounded cooler.
"Power that only humans can obtain..."
"Long, long ago, humans caught between the gods, devils, and angels—the Three Factions—were weak. They either had to submit to them or be crushed without resistance."
Now fully committed to the story, Issei spoke with growing confidence. Thanks to the information he had learned about this world, it sounded surprisingly convincing.
"But then a sage appeared. He was called the Sage of Six Paths, and he created and spread this lineage so humans could defend themselves against the Three Factions. But once humans gained power, they began persecuting and threatening one another in the same way."
"A history like that... I've never even heard of it..."
Of course she hadn't. It was all made up. ...Well, maybe not entirely made up if you counted it as a story from somewhere.
"And those who inherited that lineage later came to be called ninja, while the techniques they used became known as ninjutsu. But humans wielded power only for their own desires, attacking one another to show off their strength and dominate each other. Then, in the midst of that age of war, a ninja appeared who brought the fighting to an end. A man from the Uchiha clan named Uchiha Madara, who conquered the ninja world with the overwhelming power of the [Sharingan]. And standing against his tyranny was only one man: Senju Hashirama, the legendary ninja later praised as the god of shinobi."
"And then?"
Rias was so absorbed by the story that even she had been pulled in. At this point, he could probably make a living as a writer. No, a con artist might suit him better.
"I heard Uchiha Madara and Senju Hashirama fought for three days and nights before finally deciding the outcome. Uchiha Madara lost, and Senju Hashirama created the system of ninja villages so everyone could live in peace. But not long after Hashirama died, the struggle for supremacy began again, and in the end they destroyed themselves—except for one clan. The descendants of Uchiha Madara, the Uchiha clan. But even the last survivor of that clan died five years ago. And that person was also my master. That's the truth behind my power."
"..."
"I know it's hard to believe. Ninja are supposed to move in the shadows, so they were never recorded in history. I heard the history of the ninja was written only on the Uchiha stone tablet. I'm still searching for that tablet myself, to find out whether this history is true or false."
Issei had once read that if you tell a blatant lie while acting as though you yourself might be lying, you can block the other person's suspicion. Swallowing hard, he finished his story and watched Rias's reaction. She looked deeply troubled, as if she were seriously thinking it over.
"So you're saying you're the last inheritor of that ninjutsu? And that teleportation from earlier was one of its techniques?"
"Yes. If you don't believe me, I can show you more. For example, this is also possible: [Almighty Push]."
"This is..."
He pulled a distant object toward himself with a force like gravity, then pushed it away and drew it back at will. It was a power like psychokinesis. Rias's eyes widened. A [Sacred Gear] was supposed to be a weapon built around a single trait. For example, Kiba's ability to create demonic swords was limited to swords. But teleportation like Flying Thunder God Technique and gravitational force like [Almighty Push] were completely different categories. And on top of that, Issei also—
"Fire Release: Great Fireball Technique!"
He even spat fire into the sky. For a human, it was an impossible feat. Rias had no choice but to accept it. She herself had not yet seen the whole world and was still learning, so encountering things like this was educational as well.
"So the origin of that power was born to resist devils, gods, and fallen angels? Is there anyone else besides you who uses ninjutsu, Issei?"
"No. Unfortunately, my master seemed to think ninjutsu used for humans oppressing humans was unnecessary. He never took another disciple after me."
"I see... If that power had continued to be passed down, the balance between the factions might have changed."
It was all a lie, so that would never have happened. Unless Issei started building it up from here.
"Then did the fallen angels attack you because of that ninjutsu?"
"I'm not sure. I hadn't used ninjutsu at all before that."
"Then first, we should confirm whether your [Sacred Gear] is really inside you."
"Huh? That's possible!?"
"A [Sacred Gear] is part of the user. If the user wants it, it can be brought out anytime."
He didn't know exactly how valuable a [Sacred Gear] was, but there were ranks among them. The range was enormous, from ones that merely helped with daily life to ones that could surpass even gods. And Issei already possessed a top-class [Sacred Gear]. In return for telling her everything, Rias taught Issei how to draw out his [Sacred Gear], and as a result—
Buzzzzz
A strong vibration ran through Issei's hand, and a red gauntlet materialized on his left arm.
"This is... not Twice Critical, no, a Red Dragon?"
"A Red Dragon?"
"One of the thirteen Longinus, the Boosted Gear of the Red Dragon Emperor. It doubles the user's power every ten seconds, and can even grant strength that temporarily surpasses a Maou or even a god. You were carrying something incredible..."
The Red Dragon Emperor. In the distant past, when gods, maou, and fallen angels were at war, two dragons appeared on the battlefield of their own accord and fought duels there. The Red Dragon Emperor and the White Dragon Emperor—the two dragons known as the Heavenly Dragons—inflicted tremendous damage on the Three Factions, and the factions joined forces to stop them. As a result, one of the fragments created from sealing away the Red Dragon Emperor's soul became the Boosted Gear, the Red Dragon Emperor's gauntlet. Perhaps because of that, Rias leaned closer and touched the Boosted Gear.
"Hee... doubling every ten seconds..."
'Wait, then does that mean chakra doubles too?'
By Issei's logic, if the Ten-Tails' chakra doubled and then doubled again, it would already go beyond a divine artifact and become a cheat—something that could even approach the level of a god itself. Issei was starting to get excited, but unfortunately, there was a limit. The energy sealed inside was only at a certain ceiling, and even if he could use ten times the power, that would already be more like creation than a mere divine tool. So he suspected the amount of chakra that increased would not be all that dramatic. Still, it was certain that his physical abilities and raw power would rise. Just as Issei was thinking about how far his chakra might climb—
"!!"
Something entered Issei's detection net. It was the very same presence he had encountered not long ago—the one that had tried to kill him. Fallen Angels.
"Senpai, you said fallen angels and devils are enemies, right?"
"Yes, but why?"
"It looks like fallen angels are in this town right now. What should we do?"
"Fallen angels!? You can tell they're in town?"
"Yes. I can use detection mode too."
"Amazing... that ninjutsu of yours. So where are they now?"
"Hmm... near the church..."
"Then it has nothing to do with us. It's outside our territory."
"Huh? But if the fallen angels harm civilians..."
"Unfortunately, devils and fallen angels are officially under a ceasefire right now. If we act carelessly outside our territory, it could turn into a war, so we can't just move on our own."
"Well... I guess that makes sense... Wait, the church!?"
Issei understood political complications to some extent, so he didn't call it cowardly. Rather, he had only just realized now that he had said "the church." Yes, at the church there was a frail, delicate nun named Asia.
"Um, I'm going to head out now."
"You're not seriously thinking of going to the church, are you? You should stop. You can't handle them alone."
Rias apparently thought that since Issei had been knocked out after being caught by her, he was strong for a human but still too weak to stand against fallen angels. That misunderstanding was understandable. A jinchūriki draws on the chakra of the tailed beast inside whenever needed. So if left alone, he looked ordinary enough, and because he also concealed his vast chakra completely—on the level of Madara—his magical power appeared to be only slightly above a human's. But Issei released the shackles he had placed on himself.
"Don't worry. I'm strong!"
"That magical power!?"
Bzzzt
As he released a small portion of his power, an enormous surge of chakra poured out, and Rias's eyes went wide. Then Issei vanished before her very eyes.
"Wait, Issei!"
Before Rias could stop him, he disappeared with Flying Thunder God Technique.
.
.
.
.
.
Near the church
In a secluded patch of ground a little distance from the church, four fallen angels were gathered together.
"So, we only need to watch out for that guy, right?"
"Yeah. He looks human, but he's not. He was something completely different."
Including Raynare, the fallen angel who had attacked Issei, the three fallen angels with her were huddled together, plotting something.
"But for Raynare-nee to say that much... just what kind of guy is he? Is he a Maou or something?"
"No, he wasn't a devil. And he wasn't an angel either..."
Raynare, who had experienced the restraint of the [Rinnegan], still could not forget that sensation. The terror of being frozen before an absolute existence—she had never felt fear like that in her life, not even from Azazel. She had sworn then that she would never approach Hyoudou Issei again. But because there was something being carried out secretly in this town, there was a chance she might run into Hyoudou Issei, so she was warning her companions. And as the saying goes, speak of the tiger and it appears.
"Hey, what are you all huddled up here talking about?"
At the source of the voice, standing directly behind Raynare without a trace of presence, was Issei.
""Eek!!""
""H-He's here!!""