On the opposite side of the river, the demon father forcefully pulled out the ice spikes embedded in his body and threw them to the ground, letting out an ear-splitting roar at Hatsune, seemingly questioning why he was interfering.
"You're not one of the Twelve Kizuki? Where is Rui?"
Hatsune noticed that although the demon father had many spider eyes on his head, he didn't have the rank and number that Tamayo mentioned. Moreover, the Twelve Kizuki mostly took human forms and couldn't possibly be such a half-human, half-spider monstrosity.
Hearing the newcomer mention the Twelve Kizuki, Inosuke remembered Tanjirou saying, before being sent flying, that this was one of the Twelve Kizuki. He coughed lightly and said, "Tantaro said he is one of the Twelve Kizuki."
Hatsune didn't know who this wild boar-headed guy was referring to as Tantaro, but he knew that the big guy in front of him couldn't possibly be one of the Twelve Kizuki.
"You are not allowed to touch my family."
The white-clad girl said she was Rui's sister, so what was this big guy's identity? Uncle? Brother? Or father?
It seemed the Twelve Kizuki had created a family living on this Mount Natagumo.
The demon father waded through the river water and rushed toward Hatsune.
Hatsune glanced at Inosuke, who was sitting at the base of a tree, wearing a boar head, a pelt skirt, and bare-chested. If not for the pants that were the Demon Slayer Corps uniform, Hatsune would have thought this guy was also a demon.
No wonder the Demon Slayer Corps was so diverse, not just in the shapes of demons but also in the variety of its members.
To prevent the demon father from attacking Inosuke, Hatsune enveloped his feet in a layer of cold air. By forming ice through contact with the ground, he increased his movement speed and led the demon father away from the shore, into the river.
For Hatsune, the river water was a natural weapon.
Using the cold air at his feet to form ice on the water's surface, Hatsune floated above the water.
Inosuke, at the shore, was stunned. He had never seen such a unique breathing technique.
"Tell me where Rui is," Hatsune persisted.
"Ah~ I want you dead. I want you dead."
The demon father angrily charged at Hatsune with both fists swinging.
Hatsune didn't choose to retreat but instead faced the attack head-on. Using temperature sensing, he accurately captured the demon father's attack direction and quickly moved to dodge using the ice formed under his feet.
Water splashed as Hatsune's figure swiftly weaved through the splashes, like an illusion.
Hatsune drew his Nichirin Sword and slid under the demon father's legs, coming up behind him to slash at his back.
With a clanging sound, it felt like the sword had hit a rock, only leaving a shallow white mark on the demon father's back, numbing Hatsune's hand.
The demon father roared and swung a punch at Hatsune.
Hatsune dodged with two jumps, creating distance. In the brief exchange, he had already assessed the demon father's situation.
His rock-hard muscles provided excellent defense, and his strong body was a powerful weapon.
With his current strength, Hatsune couldn't sever the demon father's head in one blow. If he relied solely on brute force, he might end up breaking his Nichirin Sword like the guy at the tree root.
Though the cuts seemed minor, they weren't entirely ineffective, as they didn't heal instantly like typical wounds.
The demon father's massive body was a burden on his lower limbs. His movement relied on his lower body, while his attacks depended on his upper body.
After a brief consideration, Hatsune thought of another approach. If he couldn't sever the demon father's head in one strike, he'd do it in multiple. Using cold air to restrict his movement and weaken his attack power.
Hatsune took a deep breath. The cold air surrounding his body formed a white mist, and the ice under his feet began to spread.
"Ice Breathing, Combined Technique: Phantom Drift."
Hatsune's figure flickered and disappeared, engulfing the charging demon father in a swirl of snow and wind.
Only white mist remained on the river's surface. Though invisible, the growls and roars indicated something was happening within.
The white mist continued to spread, and where it touched, the water surface froze in thick layers of ice.
Another figure emerged from the forest. This time, it was Nae. She instinctively reached for her sword when she saw Inosuke at the tree root but realized he was an ally upon noticing his lower body attire.
Inosuke also saw Nae.
Having witnessed Hatsune's breathing technique at Fujikasane Mountain and Clear Water Town, Nae knew the white mist was his doing.
She didn't know what Hatsune was fighting, so she hesitated to rush in.
After a moment, a white figure leapt out of the mist, high into the air, backlit by the moon, holding a sword overhead.
The gathered mist seemed to be drawn to the Nichirin Sword from all directions.
Soon, the mist cleared, revealing the river's situation. The demon father was covered in ice flowers, kneeling in the river, surrounded by frozen water.
"Ice Breathing, Fourth Form: Snowfall."
In an instant, cold air poured out from the sword, and ice crystals fell from the sky. Hatsune swung the sword down, a white streak descending heavily onto the demon father's neck.
A thunderous noise erupted as the surrounding ice shattered and then refroze from the sword's cold air.
The demon father let out a wail, struggling, but the weight of Hatsune's sword and the relentless cold paralyzed him.
The Nichirin Sword was deeply embedded in the demon father's neck but hadn't severed it. The cold air from the blade spread, turning the demon father into an ice sculpture kneeling in the river.
Hatsune withdrew his sword and repeatedly hacked at the demon father's neck, like a butcher chopping frozen meat.
"Hatsune, let me help you."
Nae crossed the ice to Hatsune's side. She still felt guilty about the previous incident and wanted to mend her relationship with him.
Hatsune didn't look at her.
Nae thought he was still angry with her and silently drew her Nichirin Sword to help chop. The demon father's neck was nearly severed.
By now, Inosuke had fully regained his senses and stood up, leaning on a tree.
Having taken two heavy blows, his body was on the verge of collapse, especially from the recent punch to his chest, breaking several ribs.
Watching Hatsune and Nae in the river, Inosuke felt envious.
He had also thought of chopping the same spot multiple times if one strike didn't work. Though he succeeded in cutting off one of the demon father's arms, his skills paled compared to theirs.
Thinking this, Inosuke couldn't help but feel a pang of jealousy.