The Domain Expansion deployed by Naoya Zen'in: 'Soul-Bound: Revolving Lantern of the Floating World's Dream'. To put it simply, one could say this is a very 'Naoya-like' Domain.
First of all, regarding this Domain: confusingly enough, it has almost no effect on the outside world. Or rather, there is ostensibly no boundary separating the outside from the inside.
This is because Naoya has limited the deployment range of this Domain to the interior of his own body, using his skin as the outer shell.
By discarding the majority of a Domain Expansion's benefits—namely, the sure-hit, sure-kill effect on a target trapped inside—the technique imbued into the Domain is, in the end, nothing more than 'Projection Sorcery'.
—However. Naturally, that very Projection Sorcery is where the true essence of this Domain Expansion is packed.
"Wha—!?? Too fast!?"
—Even though it was blocked by the deployed Limitless technique, Naoya's speed as he 'kicked' Satoru Gojo in an instant reached Mach 33. The simultaneously generated 'Black Flash', along with the infinite barrier, blew Satoru Gojo upwards.
But the surroundings of Naoya, who should have been exerting this abnormal speed, were far too 'peaceful'.
Normally, if an object moved at high speed like Naoya's Maximum: Blue Ray, the adiabatic compression of the air alone should scatter shockwaves and cause tremendous damage to the surroundings.
But in reality, the only one generating shockwaves was the blown-away Satoru Gojo.
And against Gojo, who couldn't move freely in the air, Naoya accelerated even further, running through the sky. He dribbled Gojo repeatedly in mid-air, shaking his body around with absurd G-forces.
The sound of collisions rained down from the sky. Reaching speeds that were impossible to follow with the naked eye—or even the Six Eyes reinforced with cursed energy—Naoya flew around leaving only trails of Black Flash in the air.
Naoya retained enough reason to stick to aerial combat so as not to destroy the school building. However, the expression on his face as he one-sidedly kicked Satoru Gojo around, as if to vent his earlier frustration, revealed glimpses of joy. The current situation of one-sidedly attacking, even if 'meaningless', was truly relieving Naoya's stress.
This time of blissful punishment for Naoya came to an end because his eyes, which could look down at the ground without any influence even during high-speed movement, caught sight of Masamichi Yaga and Shoko Ieiri running onto the grounds.
Reaching his top speed of Mach 100, Naoya slammed a full-speed tackle into Satoru Gojo. Naoya and Satoru Gojo crashed into the ground—without creating a flashy crater in the schoolyard. Naoya, having dexterously changed his posture in the air, landed silently on the ground and discarded Satoru Gojo right there.
"Are ya unhurt? Honestly, I'm losin' confidence here. Normally, you'd be dead long ago."
"Urrghhh... Vuh, blegh, I-I'm carsick... Vuhhh!?"
"Gettin' off with just carsickness is weird. Ya got kicked at Mach speed and juggled like a beanbag."
Self-deprecatingly muttering to himself, Naoya released his Domain and returned to the 'world of physical laws'.
—Domain Expansion: 'Soul-Bound: Revolving Lantern of the Floating World's Dream'. Its effect is the limitless, unrestricted use of his technique on his own body and the accompanying 'automatic activation of the technique'.
During Domain Expansion, Naoya's body activates the effects of 'Lapse: Stop what is touched', 'Reversal: Freely move what is touched', and 'Lapse: Divide own movement and accelerate limitlessly' simultaneously and fully automatically.
This allows for technique applications that would be impossible under normal circumstances, such as 'ignoring air resistance completely by using Reversal to "push aside" the atmosphere', or 'kicking the air stopped just before contact to hit Satoru Gojo along with the Infinity using the spatial distortion of Black Flash'. During Domain Expansion, Naoya becomes effectively 'invincible'.
But to use an analogy, it is the invincibility of 'Mario with a Star'. That technique, which does not activate unless contact is made, still does not work on Satoru Gojo in a fundamental sense.
However, perhaps because Satoru Gojo is still developing, it seemed Naoya was able to strike a blow by kicking him all over the place, Infinity and all.
"Sensei! The idiot threw up!"
Just as Shoko Ieiri said, Satoru Gojo was vomiting, his face pale and nose running. Seeing Suguru Geto rubbing his back while directing a pitying look that said 'Is this guy an idiot?', Naoya felt he had won against Satoru Gojo at least a little bit.
Well, Naoya thought he was far from victory since his attacks hadn't reached him at all, but since the Binding judged it a 'draw', it seemed he didn't have to commit seppuku.
And in front of Naoya stood a stern-looking man with a pained expression.
"Shoko, leave the idiot who reaped what he sowed alone... Phew, er, well. I am sorry. Regarding Satoru, I formally apologize for our lack of supervision—"
"I made him puke too, so I don't mind. We'll call it even with mutual punishment. Ah, right. My kimono got torn, so if ya gimme a replacement, we're good, yeah?"
"...I appreciate your consideration. I will arrange it immediately... I am truly sorry."
Yaga bowed repeatedly to a 14-year-old. To Naoya, who had seen nothing but abnormal adults since he was born, that figure appeared so decent it was almost blinding.
But for Naoya, it was also true that he was more concerned about Satoru Gojo being nursed in the background than Yaga's behavior.
"Satoru, I think even I have to question you this time, you know? Sensei is bowing his head like crazy. Besides, once you enroll, you can spar and make any excuse you want."
"Urggghhh... Blegh... Ahhh. I guess, I guess so. If I become a junior, I can do whatever..."
"No, no, didn't you learn your lesson from this? Why are you so obsessed with him?"
"...That guy, he's stronger than me but I just can't beat him, and it pisses me off. So, if I wanna beat him, I gotta fight him... Blegh..."
"Satoru... That theory probably only works in Jump manga..."
Judging by that exchange, it seemed that 'Senior' intended to get involved with him even after enrollment.
Naoya smiled bitterly to himself, feeling that his student life would not be an easy one.
In response, Yaga, who read too much into it, ran off to have the auxiliary manager arrange a kimono as soon as possible, and there seemed to be some commotion, but that is a story for another time.