In general, while devils, angels, and fallen angels are often distinguished by the number of wings they possess, the number itself doesn't directly determine their combat strength. Or rather, it doesn't influence it as much as people assume.
Just like Leo before his breakthrough, and like Rias and Sona Sitri now—all High-Class Devils, yet still possessing only one pair of wings. That alone proves that wings don't directly correlate to power. Even without gaining more wings, they can continue growing stronger.
But there is a reason devils, angels, and fallen angels possess different numbers of wings.
A being's wings represent their tier—their "rank" as a devil, angel, or fallen angel. The more wings they have, the higher that tier is. And the higher the tier, the greater the "vessel" that carries the identity of devil, angel, or fallen angel becomes.
The greater the vessel, the higher their potential, limits, and innate qualities as a devil/angel/fallen angel. That may not directly affect combat strength, but it influences countless other things—growth rate, training efficiency, adaptability to special environments, even their recovery speed. All of these trace back to the height of one's existence.
Which is why, for devils, angels, and fallen angels, strengthening their power may be straightforward—but increasing their number of wings, increasing their rank, is far more difficult.
Take Miyamoto Musashi, for example. She's been reincarnated as a devil for several centuries. Her power is only one step away from Maou-Class, yet she still only has four wings—the level of a mid-tier devil. That alone shows how hard it is to increase wings.
For new-generation devils like Leo, Rias, and Sona Sitri, things are even harder. They may be born with astonishing demonic power and reach High-Class Devil strength by age seventeen or eighteen, but precisely because they're young, they rarely have the time or opportunity to calmly cultivate their rank as devils. And even if they do, it's not easy. So this generation generally starts with very low ranks.
Under these circumstances, it was already shocking enough that Leo displayed power equal to an Ultimate-Class Devil. But for him to then reveal four pairs of wings—eight-wing devil rank—the mental shock to all the devils present surpassed even the moment he first unleashed Ultimate-Class demonic power.
Lafei's expression twisted. His mind flooded with emotions far darker than the rage and hatred he'd shown earlier.
He—the sole surviving member of the Trix family, a bloodline not inferior to the pureblood houses of the Seventy-Two Pillars—had possessed High-Class Devil–level demonic power from birth. He'd been hailed as a once-in-a-millennium genius. Yet he only gained his first extra pair of wings after turning twenty, becoming a four-wing devil. His second pair came in his forties, making him six-winged. And he didn't become an eight-wing devil until he was well past a hundred and thirty.
He had once been proud of that. From what he knew, throughout all of Underworld history, there weren't many who reached eight wings at his age. Even in the ancient era, before the old Maou perished, during the peak of devil civilization, he could have been considered a prodigy.
But now? What was this supposed to be?
A mere eighteen-year-old new-generation devil already had eight wings?
"Why does a hybrid mutt—a half-human, half-devil—get to bear those eight wings?!"
Lafei could no longer feel rage or hatred. All that remained was jealousy. Overwhelming, mind-clouding jealousy.
"Yes… yes, that's it. I'll rip those wings off your back!"
Only then could he keep feeling proud of himself.
Lafei poured out his demonic power with no restraint. A blazing aura engulfed his entire body as he shot toward the airborne Leo like a raging meteor.
"Buzz—!"
The air twisted around him as magic circles unfolded along his sides, converting into countless turrets that fired brilliant beams of light at the retreating Leo.
"Boom! Boom! Boom! Boom—!"
Each beam smashed against the defensive magic circles Leo deployed before himself, filling the sky with flames and thunderous shockwaves, blooming like fiery flowers. Beautiful to look at—but deadly.
This was no spectacle. It was a lethal pursuit.
"Don't even think about running!"
Consumed by darkness, Lafei pushed his demonic output to its absolute limit. High in the air, he spread his arms wide, conjuring massive magic circles that locked down the space for hundreds of meters around Leo.
"Die!"
As his roar thundered out, countless attacks burst forth—magic bullets, beams, arrows, and even shapeless masses of demonic power—bombarding everything within that enormous radius, swallowing Leo's small figure.
"RUMBLE!!!"
The explosion was like the sky collapsing. The entire battlefield trembled violently, shockwaves ripping through the air like a typhoon strong enough to blow everyone off their feet.
"Leo!"
Sona Sitri—normally calm—shouted his name, fighting through the violent wind as if she were ready to fly straight into the inferno.
"Don't! It's too dangerous!"
Rias quickly grabbed her, stopping her.
Between Leo and Lafei, the clashing auras had turned the entire surrounding area into a death zone. Without Ultimate-Class Devil strength, stepping into that storm meant instant annihilation.
"Die! Die die die!"
Lafei no longer cared about anything. He unleashed wave after wave of attacks, trying to drown Leo beneath sheer annihilation.
"You were already annoying enough before. Acting like a crazed animal now just makes you look even more pathetic—third-rate devil."
A figure with eight devil wings appeared behind Lafei without warning and spoke coldly.
Before Lafei could turn, a fist wrapped in blazing demonic power slammed into his face.
"BOOM!"
He was sent flying.
"Demonic power isn't used like that, you idiot."
Leo stretched his four pairs of wings behind him—not to vent power like Lafei, but simply to gather a small amount of demonic energy.
He formed a magic bullet—no larger than a fingertip. Not a massive blast, but a tightly compressed projectile.
Lafei, tumbling through the air, saw a flash of light.
"Gah—!"
Pain tore through his shoulder as the tiny magic bullet pierced straight through.
"Guh!" "Gah!" "Gah!"
Three more shots followed, striking his abdomen, thigh, and cheek. If he hadn't moved his head at the last second, the one to the face would have gone through his skull.
"AAAAAARGH—!"
Blood sprayed everywhere as Lafei screamed, his body instantly covered in wounds.
"Damn it!"
Shock and fury twisted in his mind.
He had fought with everything he had, yet he couldn't even injure Leo—not even once. Instead, he was nearly killed in an instant.
Even if they were both Ultimate-Class Devil level—even if they both had eight wings—how could he lose this easily?!
He had been an eight-wing devil for over ten years. When he achieved that, Leo probably wasn't even born. Even at the same rank, he'd had more than a decade of training. How could he be inferior?
How was this possible?!
Lafei had no idea that Leo had been half a step from Ultimate-Class even before recruiting Shiina Mahiru as his servant. And after recruiting Mahiru—whose Longinus ranked even higher than Yukinoshita Yukino's—his power not only surged past that final barrier, but soared far into the realm of Ultimate-Class Devils.
In truth, he wasn't a newly ascended eight-wing devil. His strength was comparable to those who had been Ultimate-Class for ten or even dozens of years.
He was already stronger than Lafei.
When Lafei staggered from his wounds, Leo fired an invisible blast of compressed demonic power.
"BOOM!"
It smashed into Lafei like an unseen mountain, hurling him downward like a cannonball. He crashed into the ground, raising a huge cloud of dust.
"Damn it! Damn it damn it damn it—!"
Wracked with agony, blood spilling from his mouth, Lafei completely lost control.
"Goodbye, idiot."
Leo looked down with no emotion at all—like a true devil. No trace of his usual carefree grin remained. Demonic light gathered in his hand, clearly preparing a finishing blow.
Lafei's bloodied face twisted into something monstrous.
"You forced me!"
He roared and yanked a small vial from his clothes, a tiny black snake-like thing twisting inside.
"That's—"