Entering Sanguinem

AN. Another anime crossover with some changes :3. Seraph of the End but a twist? IDK. Oh, here's the discord link: https://discord.gg/nKgvxQvZtf

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Mikaela Hyakuya almost couldn't contain his excitement.

It's been almost three years since he and his family had been kidnapped and transported to this accursed city of the damned. Shortly everyone from the Hyakuya orphanage was taken underground, they told that humanity was all but dead, leaving the 'fortunate' children behind. Here, he and thousands of other children were raised as livestock, giving blood on a daily basis.

But it wasn't so bad. Although his brother Yuichiro hated this lifestyle, it wasn't so bad. They were given food and shelter along with the occasion toys. But what really mattered was that they were all together as a family.

Recently, he's been visiting Ferid Bathory's mansion in exchange for better treatment and food for his family. The vampire noble had taken a liking to his blood, which allowed him to keep on visiting the mansion. After familiarizing himself with the mansion, he managed to steal a map and gun from the vampire noble. It was then that a plan was set in motion.

He would take his family out of this city and into the world aboveground. After convincing and waking everyone else up, they started their great escape.

Looking down at the map, he said, "Once we get through here, we're out." Surrounding him were his brothers and sisters.

"Good," his brother, Yuichiro, said, "we're almost there." His other siblings started cheering happily at the prospect of escaping.

Double checking the map one last time, he folded it up. "Let's go."

Yuichiro smiled in turn as well. "Yeah."

Walking up the stairway quietly, the group walked down the lavishly decorated and enormous 18th century hallway leading to the exit.

'No way,' he thought. Standing not far from them was Ferid Bathory. The sight of the vampire sent shock and fear coursing through his body.

Walking down the staircase near the exit, the inhumanly attractive being smiled at their group. "I've been waiting, my poor little lambs." Stopping before the, he put a hand on his hip and smiled down at the group of children.

"Yes, that face." The vampire said, looking at the fear and anger on the children's face.

"That face humans make when their hopes are suddenly taken away." Slightly shivering at the pleasure, he continued, "this is why I can't stop playing this game."

"Game...?!" Looking at his map, he realized that something was off. Why were their no guards patrolling the streets? As the it sunk in, the shock turned to dread.

Suddenly, the vampire blurred, moving so fast, that he could no longer see his figure. Looking behind himself, he saw that the vampire was looking at them tauntingly, holding his little sister Ako in his arms, mouth open.

'No! Please, not my sister!' He thought, tears coming down his face. 'Someone, anyone! Please save my sister!'

The vampire noble took his time, slowly lowering his fangs down the defenseless girl. Just before he could sink his fangs in, the great tunnel behind the vampire exploded. From the dust cloud, he could seen a red streak of light shoot out. The vampire suddenly tossed the girl into the girl before turning around to block something.

Heat. He felt heat so hot, it was almost as if he was standing right in an oven.

Wiping the tears out of his eyes, he couldn't believe what he saw. Never in his wildest dreams would he believe he would ever see the vampire noble in such a state. The once calm and collected smile it supported was nowhere to be seen, leaving an ugly grimace. In the vampire's eyes were shock and anger at being interrupted from it's snack. But the most shocking thing was that the vampire no longer had a arm.

Standing across from the vampire was a man with long bright yellow hair with red streaks akin to flames along with two shoulder-length bangs and two chin-length bangs on the side of his head, black forked eyebrows, and golden eyes that fade to red with white pupils. He was wearing orange and white letterman jacket on his shoulder while wearing a a brown gakuran jacket, a white belt around his waist and hakama pants. From his body, a pillar of fire roared, crackling the very air around it. In his hands was a black and red blade.

"Big sis!" On the ground next him was Ako, unharmed. Akane quickly hugged the little girl while both cried. Him and the others quickly surrounded the duo while watching the standoff in front of them.

"The Flame Pillar?! You're in violation of the Vampire's Amnesty protection guaranteed by the Japanese Ministry!" The outraged vampire shouted.

"Hahaha! You dare speak to me about the law when you're farming children for blood! It seems your head no longer works for you! Allow me to remove it for you!" The flame-haired man bellowed back.

Despite the pain, the vampire forced himself to smile. "Though you may gotten lucky with my arm, it won't happen again. Even I know better than to take on the Demon Slayer Corp's strongest swordsman on by myself." With a snap of his fingers, hundreds of vampires burst through from the surrounding walls.

'No way..." Mikaela thought, 'we never had a chance did we...?'

"Even you, for all your strength, can't handle the overwhelming strength of thousands of my elite vampires, human." Ferid said condescendingly.

"Hahaha! Who said I was alone, vampire?"

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(Two Hours before)

"Sanguinem is a city located twenty kilometers underneath modern-day Kyoto. Your job is to exterminate and destroy and vampires found. The rest will be taken care of by the UN aides and agents. Any questions?" The man with glasses asked. His name was Kiyotaka Ijichi, the assistant director of Tokyo Jujutsu High.

"Um," He said, raising his hand, "when did Kyoto get vampires?" He asked.

"About fifty years ago, right WWII, most vampires in Europe were displaced by the war, so they fled and took refuge across the world. Some came to Japan, building a city underneath Kyoto. They ingeniously used holy barriers to not only prevent any of their brethren from leaving voluntarily, but to hide their presence." Kiyotaka said, showing images on his tablet. "The Japanese allowed them to stay, seeing as they weren't causing any trouble at the time."

"But recently, one of the sorcerers in Kyoto started to notice large amounts of resentment coming from down below the city. With some more digging, we found that their has been a large spike in children kidnappings in and around Kyoto prefecture." Another image of tunnels trucks entering tunnels from a distance was shown. "So the Minister of Defense asked us to handle things with 'extreme' prejudice."

"After interrogating of the vampires for information, we realized that certain conditions must be met to break in. So they called me in to dismantle the barrier to allow a small team in." He then pointed to the three sitting across from him. "That's where you three come in. While Rengoku-san and Giyu-san take on the vampires," he said, "Hachioji-san will prioritize human rescue. Any other questions?" Seeing none of them speak up, he then started walking out of the trailer.

"Well? Let's begin."

Hiding in the forest, they waited for the next truck to pass by. As soon as the truck came, he forcefully stopped it to allow Giyu to behead the driver. Signaling them to come out, Rengoku and Kiyotaka slipped in the back while Giyu and him sat in the front. They drove on until they reached the tunnel, only to be stopped by two guards.

"Halt." The guard said with a raised palm. "Identification code?" Both he and Giyu looked at each other.

But from the back of the truck, a streak of fire shot from the roof and instantly burned the two guards. Rengoku reeled in the flames emitting from him, giving his blade a swish before sheathing it.

Giyu sighed. "Did you really have to kill them that quickly? We couldn't got more information from them."

Laughing, Rengoku just shook his head. "They were assigned to guard the entrance. Now way did they anything important." He then running down the tunnel, using the fire to propel him quickly forward.

Seeing him rush ahead, Giyu sighed again before using a miniature wave to ride on.

Looking Kiyotaka, he asked the man a question. "Do you need me to carry you?

The man sighed, as if questioning how he got to this point in his life. "Yes."

Making sure the man was secured, they raced down the tunnel, lighting it up with flashes of red and green.

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After taking down the barrier to Sanguinem, Rengoku immediately shot down into the city below. Just as he was about to head after him, a hand held him back.

"Remember, Rengoku-san and Giyu-san are here to distract the vampires. The priority is rescue. Don't worry about Rengoku-san, he can handle himself."

"How about Kiyotaka-san, are you okay here by yourself?" He asked.

"Don't worry, I'm already preparing an anti-demonic barrier. I'll just stay put here and contact for the JDA to send in the cleanup crew. You go ahead." Giving the man a nod, he raced down the road to the city.

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(Present)

Explosions and screams rang out in Sanguinem as children and vampire alike were running about. But not wanting to risk the ire of the seventh progenitor, the guards continued escorting the children to the safehouse underneath the blood drawing facility. Children were quickly wrangled and put in the safehouse.

Sitting in the safehouse, Emma was scared of the noises up above. Seeing one of the younger children crying, she hugged them, caressing their head to soothe them. Behind her, Ray and Norman were discussing what was possibly happening above.

All but one vampire guard was with the thousands of children in the saferoom. The rest rushed outside to reinforce their comrades against the unknown threat. Making sure to lock the door, the heavy vault door shut tightly with a large thud.

Over the next twenty minutes, the noises got louder and louder until things finally quieted down. Emma that what ever was out there, it was getting closer and closer.

Suddenly, the vault doors were pulled off it's hinges and thrown to the side. From it emerged a figure. He was a young man wearing a dark green jumpsuit with neon green strips running across his body.

"Die-!" The vampire shouted, rushing at the two. But the man instantly appeared in front of the, giving the vampire a devastating uppercut that instantly launched the guards body out through the roof of the house. The other children instantly started backing away, afraid of this stranger.

Seeing this, Emma decided to stand up. Ray and Norman behind her tried to pull her back down, but she shrugged them off before walking right up to the man in the jumpsuit. Standing protectively in front of the other children she asked, "Who are you?"

The man - no, looking closer, he seemed more like a boy - smiled at her. The way the light from above shinnied down on the teenager; it almost as if he was a angel.

Getting down on one knee, he looked at the girl in the eye.

"I'm Deku, and you're safe now."

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"Hahaha! Who said I was alone, vampire?" Rengoku shouted.

Several screams erupted from the group of vampires as heads went flying. Appearing next to Rengoku, Giyu looked annoyed.

"Why did you rush ahead? You're impatient as always."

"Hahaha! Giyu, you seem as bored as usual. I take that armless one right there! You can take the rest."

"Tsk."

Without waiting, Rengoku burst forward, propelled by his flames toward the vampire noble. Seeing his friend take the fight outside the building with the vampire, looked at the group of kids behind him.

"Hey," he said to them. Getting their attention, he continued speaking. "Don't move around, or I can't promise that you won't get hurt." Hearing that, all the heads furiously nodded.

Focusing on the vampires surrounding them, he prepared to slaughter them.

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Strong.

Those were the words that came to Yuichiro Hyakuya's mind.

The man with the mistmatched haori swung his blue blade. Each time the man swung, bodies and heads would go flying.

Before the fight started, the man had summoned water, covering the floor in water. Water tentacles circled the man as he fought, acting as a shield and second form of attack He flowed back and forth between the enemies as if he was made out of water.

Then the man got into a strange stance. "Twelveth Form:-."

*Philp* *Plat*

Looking up, Yuichiro realized it started raining indoors. Then he started to hear the screams around him. Looking back at the battle, he was shocked.

"-Rainfall."

As if knives, with every raindrop, the vampires were being cut into pieces. After a couple of more seconds, the once filled room was cut down to none, leaving a man and children left behind.

Sheathing his sword, the man with haori looked above, before turning to them. "Follow me if you want to live." With that, the man started to leave.

Looking at his family, they silently looked at each other before getting up to follow the man.

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The streets echoed the clash as the demon slayer and vampire fought.

Long gone was the Ferid Bathory with inhumanly good looks. His true form was revealed, showing a humanoid bat with bulging muscles and long sharp teeth. The creature sent a screech, causing the earth to shake and the air to vibrate.

Unaffected by it, Rengoku continued swinging his sword at the vampire which prevented it from regenerating by cauterizing it's wound. Thinking this would do the vampire noble in, he was surprised when the it gnawed at the burns to allow it to quickly regenerate.

The vampire screeched once more before manipulating it's blood into scythe and hardening it. Giving the Flame Pillar a bloodthirsty grin, it charged head on.

The two dueled, with Rengoku using his sword to cut the vampire and his flames to evaporate the blood before it touched him. The vampire forgone all technique, using it's berserker-like style to stay unreadable to it's enemy.

The vampire started laughing. "You were a fool, Flame Pillar! Now, you are doomed! Not even the Third Progenitor can handle this attack and come out unharmed!" Retreating, the air around the vampire started to turn cold as blood started flowing outwards, forming wings.

"Die!" Shooting the blood wings, the blood turned into a red mist that caused the surrounding air to lower dangerously below freezing point.

Smiling, Rengoku did not falter as he got into a stance. "First Form:-."

Sure of his victory, the vampire was turning around when he felt the start to raise in temperature.

Shooting through the blood mist was Rengoku, blazing with fire.

Seeing the Demon slayer quickly approaching him, he tried to quickly create a blood shield, but he was too slow.

"-Unknown Fire!"

Ferid Bathory watched as the world slowly turned upside before all he could see was flames.

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Guiding the children through the tunnels, the trio and children were greeted to the blinding flood lamps that shied down on them alongside numerous military and medical personnel that immediately rushed towards the children.

Even though it was a weekend, his parents would still be worried. And he hadn't had decent sleep the past couple of weeks due to the multiple missions he had.

"Mr. Deku?" Looking down, he saw a child shyly tug at his pants. "Could you please stay with us?" She said with hopeful eyes. He noticed that numerous other children were looking at him as well.

'Well no sleep today either.' But contrary to his thoughts, he was smiling.