Starting with No Game No Life: Infinite Chests

"Mmm, it'll still take a while before I can fully adapt to this unknown energy. For now, I have to rely on my stored 'spirit energy.' It feels a bit uncomfortable," Jibril said, slightly uneasy.

"No need to make it so complicated." Riku shook his head and, using the authority of the Star Grail, granted Jibril the ability to convert energy.

While his higher-level powers were sealed since he hadn't claimed the World's Authority here, something like this was still within his means.

"Riku, I don't need it. I'll finish analysing and adapting to this energy structure soon," Schwi said softly as Riku glanced over.

He smiled and patted her head. 'She's trying not to trouble me.'

"Ahh, that's much better," Jibril sighed in relief, stretching. "Still, what exactly is this power?"

"This energy here is called 'magic power.' Before long, you'll also see 'holy power,' 'spiritual power,' and other types," Riku explained. "Well, it's a bit complicated to break down, but you'll get to experience it firsthand. This world's power system is far more complex than Disboard's; there's more than just 'spirit energy' here."

"Is that so? Now I'm looking forward to it!" Jibril's eyes sparkled with curiosity.

"Riku knows so much. Have you visited here before?" Schwi tilted her head, asking.

"You can think of it that way." Riku grinned, ruffling Schwi's hair again.

She didn't press further, just nodded quietly.

"Looks like it's getting dark. Let's go find somewhere to stay." He glanced at the darkening purple sky.

With that, Riku, Schwi, and Jibril vanished from the spot.

At that very moment, a black sphere of magic struck the spot where Riku had just stood, landing on the castle of the Naberius Clan, one of the pure-blooded devil noble families.

With a thunderous explosion, the castle nestled in the beautiful forest was swallowed by energy and annihilated.

The shockwave rocked the nearby city, leaving every devil there staring in disbelief, unable to comprehend what had just happened.

Meanwhile, Riku and his companions strolled through the city ruled by the Naberius clan, Naberius City, for the first time. Even Riku, upon seeing the capital of the devils, felt a tinge of excitement and casually went out to explore.

Jibril, of course, shrank her wings and kept them hidden.

Many devils noticed how odd the trio looked, but thought little of it.

Riku, unbothered, found an inn and checked in. With the system's built-in translation, language was no issue; as for money, he simply tossed a few gemstones from Disboard.

"Master, is it really okay for us to be staying here so leisurely?" Jibril asked curiously. "If we're discovered, the devils will probably come after us in force."

"Silly Jibril," Schwi replied quietly. "Riku's plan is for them to come find us."

"Exactly." Riku smiled, "Chasing them down one by one would be too troublesome. It's much easier to let them come to me."

"So for tonight, we just wait for our 'guests' to arrive," he added, nonchalantly.

"Sigh, is that so? I guess that means we can't 'play games' with Master tonight," Jibril said with exaggerated disappointment, especially stressing the word 'game.'

"Riku, let's play chess. Jibril, you can just watch," Schwi huffed, producing a chessboard.

"Heh, that'll pass the time nicely." Riku grinned. Among his favourite things: fighting powerful opponents, wandering with his women, lovemaking and of course, playing chess with Schwi.

Soon, Riku and Schwi were absorbed in their match.

"Excluded again... But I guess it can't be helped," Jibril muttered, watching the two, who were both entirely focused on the game. "After all, I'd just get steamrolled if I played against Master and Schwi..."

While Riku and Schwi played chess in leisure, all hell broke loose across the Underworld.

At dusk, the ancestral manor of the pure-blood devil noble Naberius clan had been obliterated by terrorists! Every last devil in the household, including the young lord of the Naberius Clan, was dead!

Since the great war between God, Lucifer, and the Fallen Angels, pure-blooded devils had become extremely rare; each one was a vital link in the devils' bloodline. The loss of even one was a catastrophic event, let alone the total annihilation of a main house, right in their own domain. It was a direct slap in the face to the Underworld.

The upper echelons of devil society were furious. An emergency summit was called, drawing even the Four Great Satans together.

No one knew the culprit's identity yet, though it was suspected they possessed at least Ultimate-class strength. Even the Satans weren't certain, but this was a matter of the Underworld's honour; if not dealt with properly, their prestige would suffer.

Information spread at lightning speed. In just a few hours, every devil with even the slightest interest in current events knew what had happened.

Most were shocked and indignant.

The one most enraged was the clan head of Naberius, the Ultimate-class devil and lord of the city. His only son had been slaughtered in his own home, no less!

Fury and humiliation boiling over, he ignored the summit entirely and launched a personal manhunt.

Within hours, he had locked onto Riku's location at the inn, hardly surprising, since Riku hadn't bothered to hide.

That level of contempt nearly made Nigel explode.

With hatred and rage overflowing, he gathered his peerage, closest retainers, and every devil soldier he could muster and rushed toward the inn.

Such a commotion couldn't go unnoticed. Within moments, bold devil civilians trailed behind, eager to see what would happen.

"I win again. That's 100 wins, 100 losses," Riku said with a smile.

Schwi puffed up her cheeks, sulking. Riku was getting more and more 'devious.'

"Again," she said, pouting.

"Let's do it next time. For now, our 'guests' have arrived," Riku said, ruffling her hair.

"Fine," Schwi sighed, putting away the chessboard.

Jibril, meanwhile, was already cracking her knuckles in anticipation.

"They're right here?" The middle-aged devil radiated an overwhelming aura and murderous intent as he questioned his subordinate.

"Yes, Lord Naberius. This is the place. They didn't even bother to hide themselves earlier; they brazenly wandered around the city before settling in at this inn." The subordinate, also emitting a powerful aura, responded respectfully.

"Hmph, how arrogant can you get!" Nigel Naberius' expression grew even darker. As a veteran of the Great War and a devil named in the Bible, when had he ever been so humiliated?

"Tear this inn to the ground. Force them out," Nigel Naberius commanded, eyes filled with killing intent.

"Understood." His subordinate instinctively wanted to remind him there were innocent devil civilians inside, but remembering his master's ruthless nature, he simply nodded and prepared to follow the order.

A huge fireball formed in his hand and was hurled toward the inn.

In an instant, the entire building was engulfed in flames.

But before even a second passed, the fire was forcibly repelled an invisible barrier enveloped the inn.

"A barrier? What is this power?" Nigel Naberius frowned, sensing an energy utterly unlike magic power, holy power, or spiritual power. He felt a chill down his spine.

"Hmph, you think a little barrier will let you act with impunity?" With a cold face, he summoned jet-black flames in his hand, warping the space around them and sending the temperature soaring.

"Really, no sense of manners. Just attacking the moment you arrive," A lazy voice echoed, drawing every devil's gaze upward.

Atop the roof stood three figures: Riku, Schwi, and Jibril.

"So, the criminals who killed my son finally decided to show themselves. In that case, die!" Nigel Naberius' killing intent locked on Riku, and with a roar, he hurled the black flames.

The flames twisted into a dragon, roaring toward Riku.

Every devil present watched coldly; they all expected these intruders to be dead already. After all, their lord was a survivor of the Great War, an Ultimate-class devil, second only to the Four Satans themselves.

But Riku just waved his hand, looking bored.

Suddenly, a storm erupted. The black flame dragon, which had seemed so fierce moments ago, was instantly blown apart, its cinders scattering and igniting everything nearby.

The tempest tossed many devils aside, even causing Nigel Naberius himself to stumble.

Barely regaining his footing, he stared in horror at the devastation. With a quick motion, he tried to pull back his flames, but couldn't hide the fear on his face.

A casual wave had wiped out his most powerful attack. This man was far too powerful!

Nigel had originally assumed Riku was merely Ultimate-class. After all, encountering a Satan-class being in the Underworld was virtually impossible, especially someone unknown.

But now, he could only tremble in terror. Satan-class? Could even a Satan casually generate a storm that shattered his most furious strike? It was absurd!

"What, scared already? How boring."

Riku's tone was flat. By this point, he'd figured out the basic power levels of the High School DxD world: Ultimate-class devils were comparable to average Flügel from Disboard, maybe even a bit weaker, since Flügel could use the busted 'Teleport' ability.

"If that's all, then you can die now," Riku pronounced Nigel Naberius' fate with complete indifference.

"W-wait—!" Nigel's scalp went numb. He tried to say something more—

But before he could, Riku casually punched forward.

The terrifying shockwave blasted through the air, obliterating every devil, above blood rained down on the city below.

"How dull. Schwi, let's go back and keep playing chess." Having wiped out the Naberius Clan in a single blow, Riku barely seemed to care. If you target him, you'd better be prepared for the consequences.

"Mm. Chess. This time, I won't lose," Schwi said, eyes burning with determination.

"Heh, I wouldn't be so sure," Riku replied, grinning.

"Mmm, I wanted to play chess too... It's so boring now. I thought I'd get a fun fight, but Master finished everything in a flash," Jibril pouted.

"Shut up, Jibril, you're too weak," Schwi replied deadpan.

"Ahh, a critical hit~" Jibril smiled, feigning pain.

"Gulp—"

While Riku's group joked and headed back to the inn, a crowd of devil civilians who'd witnessed the battle could only swallow in fear, their bodies trembling uncontrollably.

Terrifying. Where did this monster come from? He'd just swatted aside the pure-blooded devil Ultimate-class Nigel Naberius like he was nothing!

A whole noble clan, annihilated in a single day and right here, in the Underworld, in their own city. It was an incident that shook the entire world.

No one could imagine what would happen next. Riku was simply too strong. Even those who always believed the Four Satans were invincible found their faith shaken.

Back at the inn, Riku had already set up a suite of wards, soundproofing, defences, alarms, all kinds of layered barriers. There, he played chess with Schwi and 'games' with Jibril.

But the news of what happened here spread like wildfire, shaking the Underworld all over again.

And when word got out that Riku had killed Nigel Naberius, the Ultimate-class patriarch, and was still calmly staying at the inn, devil nobles and commoners alike nearly lost their minds.

He was utterly disregarding the Underworld's authority. This was beyond reckless!

Especially at the Council of Elders, where the atmosphere was so tense you could cut it with a knife. Even the Four Great Satans frowned.

This guy was truly outrageous and, worst of all, he actually had the strength to back it up.