This was Lava Release.
Lava Release formed when earth and fire mixed!
Lava Release was a Kekkei Genkai produced by combining earth and fire chakra. In the Naruto anime, it had only been used by Rōshi, the Four-Tails Jinchūriki of Iwagakure in the Land of Earth.
Although Rōshi had been defeated by Kisame Hoshigaki, who extracted the Four-Tails Son Gokū from him!
Rōshi's strength was not to be underestimated. He had once fought Naruto Uzumaki, the Nine-Tails Jinchūriki, and Killer B, the Eight-Tails Jinchūriki, using Lava Release Chakra Mode, and burned Naruto. Clearly, Lava Release was an extremely destructive Kekkei Genkai.
As for his battle with Kisame, that was because Kisame Hoshigaki possessed Samehada, one of Kirigakure's Seven Ninja Blades. Samehada was a fish that lived inside the Three-Tails Isobu and helped the Three-Tails absorb and consume chakra. It could extract five times as much chakra from food as could normally be extracted.
It was precisely because he possessed Samehada that Kisame Hoshigaki had chakra on par with a Tailed Beast and could unleash Water Release Ninjutsu on a level comparable to the Second Hokage's. Samehada could counter ninjutsu, while Water Release techniques of that level could counter Lava Release—
Even with so many trump cards, Kisame Hoshigaki, who possessed Kage Level strength, had not found it easy to defeat Rōshi, the Four-Tails Jinchūriki.
Excitement shone in Sato Hideaka's eyes as earth and fire chakra slowly gathered in his right hand. Dark red, searing lava swirled over it, covering his hand. Its heat scorched the surface of the wooden houses nearby.
More and more lava gathered, and the weight his right hand bore grew heavier—
He leaped off the wooden floor and onto the grass, then dashed toward a rock half his height. The dark red lava around his right hand seemed to take the shape of a canine.
[Lava Style: Hell Hound]
His right hand, wreathed in searing lava, plunged into the hard rock. As the magma formed the shape of Akainu's head, countless jets of lava burst out, melting the half-height rock away!
Sato Hideaka took several deep breaths, but couldn't hide his delight. "Hellhound" was a technique he had modeled after one of the strongest fighters in One Piece: Akainu (Sakazuki), one of the Navy's Three Admirals.
Akainu (Sakazuki) possessed the Logia-type Magma-Magma Fruit. Judging by his fight against Whitebeard at Marineford, the Magma-Magma Fruit might not match the Tremor-Tremor Fruit in its destructive power against nature and buildings, but it was more lethal to living beings.
And Hellhound was one of Akainu's signature techniques. Its destructive power was astonishing. He had blown off half of the world's strongest man Whitebeard's face (in the anime, he pierced his abdomen) and punched through the chest of Fire Fist Ace, son of the former Pirate King Roger.
It had explosive power, short range, and high attack potency.
Sato Hideaka had only wanted to recreate the scene in his mind in the real world. He hadn't expected it to go so smoothly. The lava had taken the shape of a dog—this must have been chakra shape transformation.
After Lava Style: Hell Hound pierced the half-height rock, the searing lava melted it completely. The rock turned into a stream of molten material that sank deep into the soil, scorching the ground around it and unleashing searing heat and flames...
In terms of destructive power, it should rank somewhere between A-rank and S-rank ninjutsu. It was no weaker than Kakashi Hatake's self-created Chidori!
"That's incredible, Hideaka! Where did you learn that move? How can it be so powerful?"
"Hideaka, big brother Hideaka is amazing!"
"Th-this is ninjutsu? It's so amazing, so cool! I want to be a ninja just like Hideaka!"
The children in the yard were completely stunned. They had already envied Sato Hideaka when he first gathered chakra, then learned to climb trees and walk on water, and even played on the roof.
And now Sato Hideaka had punched a solid rock out of existence. It was amazing!
"Hi... Big Brother Hideaka, Mai wants to learn too! I want to learn!"
Three-year-old Fujiwara Mai stretched out both hands and hurried toward Sato Hideaka on her short legs. The heat made her face glow red.
Sato Hideaka scooped Fujiwara Mai into his arms and planted a big kiss on her apple cheeks, then carried her away from the lava. Lava Style: Hell Hound was simply too destructive. The spot where the rock had stood had become a pool of lava, and it was still sinking into the ground.
If anyone got too close by mistake, they would be burned by the heat!
"Once Mai-chan grows as big as Big Brother Hideaka, I'll teach you. How about that?"
Fujiwara Mai scrunched up her face and vigorously wiped away the saliva Sato Hideaka had left with his kiss, looking disgusted. "How could you kiss Mai's face, Big Brother Hideaka? Big Sister the matron said boys can't kiss girls. Unless Big Brother Hideaka becomes Mai's big sister..."
Sato Hideaka's forehead creased with exasperation. He'd almost forgotten that embarrassing incident, but the girl had brought it up again. She had been the one who called him "big sister" when he first arrived at the orphanage, and now she was at it again.
"Mai-chan, if you keep this up, watch out—your chubby face might turn square."
Sato Hideaka put Fujiwara Mai down. Ignoring her struggles, he pressed both hands to her cheeks and kneaded them mercilessly. Her soft, chubby face felt wonderful.
The lava didn't go out until two and a half hours later. Another half hour passed before Yakushi Nonō returned to the orphanage. Seeing that the spot in the backyard where the artificial hill had stood was now a charred crater, she couldn't help asking,
"What happened while I was gone? What on earth is this?"
"Hideaka did it! He invented a ninjutsu that makes his fist catch fire. He melted that rock with one punch, and the fire didn't go out for half an hour!"
The speaker was the older boy, Horibe Ryuichi. Compared to Sato Hideaka, who was seven years younger than him, he felt like an idiot. He'd fallen after just two steps while trying to climb a tree, and he'd never managed to stand on the lake's surface when trying to walk on water. And as for ninjutsu—
He hadn't even started learning it, while Sato Hideaka had already invented a technique that powerful!
But compared with the other children his age, he had been the first to gather chakra. He wasn't as weak as he'd imagined. Still, compared with Sato Hideaka, the gap was far too great...
Looking at Horibe Ryuichi's dejected face, Yakushi Nonō didn't know how to comfort him. In terms of talent, Horibe Ryuichi was already above average, but compared with a prodigy, the gap was like a chasm.
Perhaps this world simply had prodigies who stood above everyone else!
Still, as she looked at the charred crater, Yakushi Nonō found it hard to believe Sato Hideaka's ninjutsu had done this. Ninjutsu didn't usually leave this kind of destruction. The rock had been burned away, and the ground had even become a charred crater. Was there a Fire Release Ninjutsu that could do that?
Or had it been caused by some other kind of attack, like Lava Release, a Kekkei Genkai?
Yakushi Nonō frowned and asked, "Ryuichi, do you know where Hideaka is now?"
"Hideaka took Mai and the others to the river to play at walking on water..."
Yakushi Nonō hurried to the river in a few quick leaps. Sato Hideaka was standing on the water, carrying a child of about three as they played. A group of children stood on the bank, watching enviously and shouting that they wanted to play too.
Yakushi Nonō and the other orphanage teachers had warned the children not to go near the river, since it was dangerous. But ever since Sato Hideaka had gathered chakra and learned to walk on water, he occasionally took a group of children there to play.
Yakushi Nonō knew about this. Sato Hideaka was more mature than other children and always thought things through, so she felt comfortable leaving them in his care. After all, it was better to guide them than forbid them. Learning to swim was another useful skill for the children.
She would just have to remind them, along with the other teachers, not to play by the river unless an adult or an older brother or sister was there to look after them!
Yakushi Nonō reached the riverbank. The children crowded around her, chattering excitedly about wanting to learn ninjutsu and become ninjas. They were clearly envious of Sato Hideaka, who could stand on the water.
"Hideaka, come here! I need to ask you something!"
After saying a few words to the children, Nonō waved to Sato Hideaka in the middle of the river and called out.
Holding the child in his arms, Sato Hideaka skimmed across the water amid the child's excited squeals, then leaped onto the bank and came over to Yakushi Nonō. He put down the child, who had clearly wanted to keep playing.
"What is it, Big Sister? What did you want to ask me?"