Flaming Thunder God.
As previously mentioned, this was a sword form that originally didn't exist in Thunder Breathing.
Original Thunder Breathing had a total of six sword forms: Thunderclap and Flash, Rice Spirit, Thunder Swarm, Distant Thunder, Heat Lightning, and Rumble and Flash—from the first to the sixth sword form, there was no such thing as the seventh sword form.
However, Agatsuma Zenitsu, who could only use the first sword form of Thunder Breathing and could not wield the other five, pushed past his limits through sheer effort and reached a realm that no other users of Thunder Breathing had achieved.
By focusing solely on perfecting the first sword form, he honed it to the absolute peak, developing extension techniques like 'Thunderclap and Flash - Sixfold', 'Thunderclap and Flash - Eightfold', and 'Thunderclap and Flash - Godspeed'.
Through this process, he combined elements of the other sword forms and created his very own unique sword form, which was the seventh sword form of Thunder Breathing—Flaming Thunder God.
Not only did it possess speed and explosive power that surpassed even 'Thunderclap and Flash - Godspeed', but even when used by Zenitsu, it allowed him to move at such extreme speed that an Upper Rank couldn't even see his attack, as his slash left behind the image of a golden thunder dragon, making it look as if lightning itself was soaring through the air.
Its power was so overwhelming that even an Upper Rank, normally giving even a Hashira a hard time, would be instantly decapitated if struck by this sword form.
One should know that when Zenitsu developed this sword form, his strength was only at Level 3—meaning he hadn't even reached the strength of a Hashira. Yet, after mastering this sword form, he became capable of delivering a fatal threat to even Upper Ranks whose strength was at Level 4, which proved how powerful it was.
Riezel had already been interested in studying Flaming Thunder God the moment he learned Thunder Breathing, so while refining the thirteenth sword form of Sun Breathing, he smoothly grasped the structure of Flaming Thunder God and figured out which sword forms Zenitsu had likely combined to create it.
As a result, Riezel successfully recreated it, incorporating his own understanding into the mix and even infusing some of the essence of Sun Breathing's thirteenth sword form into it, making Flaming Thunder God even stronger and more terrifying than in the original work.
As expected, the outcome was astonishing.
Now that Riezel had reached Level 7, Flaming Thunder God exploded with unimaginable power in his hands, completely overwhelming Raven, who had launched a desperate attack.
Riezel could feel that as the entire training field was engulfed in a blinding white light from the deafening explosion and impact, his golden lightning slash had struck Raven's body, shattering the armor he wore.
Raven was swallowed by the golden lightning, blood spurting from his body as he crashed into the collapsing ground.
Nonetheless, that didn't mean Riezel had it easy either.
Raven's Rebellion was known as the weapon with the strongest attack power in Jinas. Not only was its sharpness astonishing, but it also possessed various special effects, especially magic breaker and defense breaker, allowing Rebellion to pierce through all of its target's defenses upon impact.
Against this sword, even Body of Effulgent Heliodor, a magic spell that nullified slashing damage, was useless because Rebellion's magic breaker effect would bypass any magical defenses, directly damaging its target.
Even if Riezel had raised a massive shield and worn heavy armor, it wouldn't have mattered either since the defense breaker effect would have effortlessly shattered any armor's protection unless its quality exceeded that of Rebellion.
Moreover, Raven had recklessly pushed himself to the limit, fully unleashing the Dark Abyss Sword Style, which boosted his strength far beyond his normal level. If his attack had landed cleanly on Riezel, even with his current strength, he would've suffered severe injuries.
Fortunately, at the last moment, Riezel activated the ability of Divine Meloe, placing himself in an invincible state for one minute, completely nullifying Raven's desperate strike.
Divine Meloe truly lived up to its reputation as an ancient mystical treasure capable of stirring something within Riezel, proven by how its power remained unbroken even by a powerful weapon like Rebellion, leaving him completely unharmed.
Even so, at this moment, Riezel felt like something was off.
'Where the hell is this?'
Riezel stood frozen for a moment because he realized that he was now in what appeared to be a massive cave. All around him were walls and stone, with a rocky ceiling overhead and no signs of any man-made structures.
It was so abrupt.
Just a second ago, he had been in the grand and meticulously crafted training field, and now, as if he had been thrown into the depths of some remote wilderness, he found himself in a vast underground cavern.
No matter how he looked at it, the situation felt bizarre.
'Don't tell me... this place is beneath the training field?'
Riezel could only think like this.
Because of that earth-shattering collision, the entire training field collapsed, causing not only Raven to fall into the depths, but also burying Riezel under a massive wave of rubble and debris.
However, Riezel wasn't worried because, with Divine Meloe protecting him, he knew he was safe for at least a minute, so he let himself sink into the ground, planning to wait until Divine Meloe's isolation effect wore off. As soon as he reconnected with the outside world, he would immediately use teleportation magic to leave.
Given that circumstance, it made sense for Riezel to assume he was still beneath the training field, but who would've thought that there was such a massive cavern beneath it?
Regardless, this didn't make any sense.
First of all, if he had fallen from above, then why was there an intact rock wall above his head instead of a hole?
Riezel was starting to feel like something was fishy.
'Something's wrong here...'
Riezel activated the Transparent World without hesitation, making his eyes gleam with a transparent light as he scanned his surroundings.
As soon as he did, his pupils shrank.
What had seemed like ordinary walls and rock surfaces in this cavern weren't actually rock but writhing masses of flesh.
Thanks to the Transparent World, Riezel could clearly see the way the flesh pulsed, the veins hidden beneath it, and even the slimy fluids oozing from the cracks between the so-called walls and rock surfaces—something he hadn't noticed before.
Apparently, this place was—
'Am I inside a living creature?'
As soon as Riezel realized this, something happened.
*Rumble—!*
With a loud rumbling sound, the entire cavern suddenly trembled violently, like a massive beast that had been startled awake.
Riezel was flung into the air, nearly slamming into the mucus-covered ceiling, but—
"Fly!"
Riezel immediately used flight magic, his body flickering with a ghostly blue glow of magical energy, allowing him to hover midair to avoid the disgusting impact.
Unfortunately, the disturbance had only just begun.
*Buzz—* *Buzz—* *Buzz—* *Buzz—*
A piercing, buzzing sound filled Riezel's ears as the cavern shook wildly.
In the next moment, countless black silhouettes swarmed from the far end of the cavern.
With wings flapping at an incredible speed, producing nerve-wracking buzzing sounds that made one's scalp tingle, they had hard exoskeletons and looked like beetles, but bizarrely, they were the size of cows.
"Monsters...?" Riezel muttered, his body frozen.
Why were there monsters here?
Wasn't this inside a living creature?
He had no idea how he had even gotten to this place, but if this really was inside a living creature, then how could there be monsters nesting here?
*Buzz—* *Buzz—* *Buzz—* *Buzz—*
Ignoring Riezel's confusion, a swarm of giant beetle monsters flapped their wings furiously as they rushed toward him—the scene had the overwhelming feel of an insect swarm surging forward, making Riezel a little uneasy.
"Anti-Life Cocoon!"
Not wasting any more time, Riezel immediately cast a defensive magic, summoning a protective barrier that glowed with a hazy light.
*BANG!* *BANG!* *BANG!* *BANG!*
*BANG!* *BANG!* *BANG!* *BANG!*
One by one, the giant beetle monsters slammed into the barrier that had suddenly risen, triggering a series of loud impacts before being sent flying, unable to even get close to Riezel.
*Buzz—* *Buzz—* *Buzz—* *Buzz—*
As their attacks failed, the beetle monsters became even more agitated, with some desperately ramming against the barrier while others simply clung to it, gradually covering its entire surface.
"Not gonna lie, this is so disgusting..."
Even Riezel couldn't help but feel repulsed by the sight.
"Negative Burst."
Riezel cast another magic without hesitation—this time, a ranged offensive magic.
In an instant, a black wave surged outward from him, spreading like an explosion, devouring everything in its path, which made the beetle monsters clinging onto Anti-Life Cocoon, along with the surrounding monsters, get engulfed in the black wave.
In an instant, the beetle monsters surrounding Riezel vanished on the spot.
Negative Burst, unlike Decomposition Magic that completely erased its targets, made its targets' bodies seem to explode apart as if their very structure had been torn apart, disintegrating into unknown particles that scattered into nothingness.
Now that the giant beetle swarm was gone, Riezel's field of vision finally cleared, and the sickening sight of beetles crawling all over had vanished.
Sadly, the relief was short-lived because the beetle monsters were still pouring in from the other side of the cavern, their numbers seemingly endless. As they swarmed forward, their incessant buzzing drilled into Riezel's ears, making him feel increasingly irritated.
"Tch, this place isn't safe to stay for long..."
Riezel frowned, uncharacteristically hesitating.
As powerful as Riezel was, even he had no desire to recklessly charge into a disgusting swarm of giant beetles for a fight, so he decided to use teleportation magic and leave the place immediately—until he saw several black-robed figures.
*Swish!* *Swish!* *Swish!* *Swish!*
Using the Transparent World, Riezel could see several black-robed figures move in complete silence, ghostly and elusive, appearing in the cavern like ghosts.
Seeing them, Riezel, who had been about to use teleportation magic to leave, stopped.
No choice.
At this moment, their eerie movement techniques, ghost-like presence, and lifeless bodies without hearts were all revealed through the Transparent World.
Needless to say, these black-robed figures were just like the mysterious attackers who had kidnapped Lizbeth.
Riezel halted, his gaze locking onto the black-robed figures with a cold glint surfacing in his transparent eyes.