This is chronologically taking place:
in Blood+ : after episode 45.. (actually just watch the whole series and then read this :P)
in Katekyo Hitman Reborn: ...well.. let's just say after the battle of Tsuna with Mukuro
An unexpected encounter
Blood... That's all their eyes were seeing. One after another, terrible vampire monsters laying on the ground with their blood spreading all over the place. Saya knew she had no choice, yet she couldn't accept this cruel fate of hers. She couldn't accept who she was.
"Saya, we have to go."
Her reserved loyal servant reminded her that they didn't have much time ahead of them. Another vampire had been located in a nearby area, thankfully, a remote one. The young girl prepared her katana and Haji was already waiting for her downstairs.
Both of them resided in an old house, where the horrible smell of carrion surrounded the place. 'A home fit for me' was what Saya said when she first came across it. Haji hated watching his beloved master so despondent but as a loyal servant he could do nothing else but agree with her choice.
-at the same time in another place-
"Is this it?"
The Sky Guardian looked around him in disbelief.
"Yes, that must be it. Rebor-san's instructions indicate here. Look Jyuudaime."
The silver haired boy showed the small map to his boss but the single lines and arrows confused him greatly.
"Ah, okay-okay!"
He nodded hopelessly of his obtuse nature.
"I thought we were here for a challenge TO THE EXTREME!"
"Ma ah~ Maybe the baby is hiding somewhere among the trees."
Yamamoto pointed towards the forest behind them.
"That's not possible you idiot! We came here through the forest! Reborn-san would have showed his face until now!"
The Storm Guardian shouted angrily.
"I have no idea what he has in mind..."
Tsuna monologued to himself as he turned his gaze on Yamamoto's hands where one of his Guardians, Lambo, was taking a nap. He hated the fact that they had to drag Lambo along with them. He was too young for the battles; as for the challenge, the Sky Guardian didn't even wanna imagine what his tutor was planning.
The five boys were standing in a secluded area, staring at the vast space, trying to find some kind of clue for their challenge. Solid ground was laid in front of them and a rickety abandoned building was standing some kilometers away.
"Ah, it's creepy here..."
The young boss said apprehensively.
"Don't be afraid Jyuudaime! I..."
A loud scream covered Gokudera's voice.
"What was that?"
Ryohei shouted as all the Guardians shifted to their defense positions; the five boys were ready to defeat whatever made that sound.
They were all standing quiet waiting for a move from the enemy. The scream that was heard, didn't sound human so the boys were feeling somewhat nervous of what was about to appear. All of a sudden two more screams were heard as if the enemies had been multiplied.
"Hieeek!"
A squeal escaped from the young Vongola boss. Being able to only hear the enemy agitated him greatly. What if a person with superhuman powers showed up in front of them? What if a being with six hands attacked from the trees behind them? Tsuna jolted at this thought. He turned his body towards the trees and sighed in relief when he didn't see any weird creatures.
"Jyuudaime, be careful!"
The loud voice of Gokudera startled the brunette and as he turned around he saw a creature, bigger and more frightening than the ones he had imagined. It was a real monster.
"Ah!"
Tsuna fell on his back with his hands covering his face, while the monster was screaming in pain, receiving the attacks of the Vongola Guardians. Two more monsters had made their appearance and all three of them seemed impossible to beat. Dynamites, punches in the speed of light and even sword attacks, everything was happening too fast, yet there wasn't any progress in their battle. As if the monstrous creatures were coming back to life, the attacks had no effect on them.
The young boss was looking terrified at his friends who were trying to protect him and protect each other; he knew he had to fight. Moreover their enemy was not a human being, so he wouldn't hold back this time.
"Everyone, stay back. Leave these monsters to me."
He said as a flame was radiated on top of his head, ready to fight in order to protect his friends.
As Saya and Haji were reaching their destination they started hearing explosions and the chiropteran screaming hysterically.
"What is that?"
Saya looked alarmed at Haji.
"There are probably some people amongst them."
Her chevalier replied calmly, making Saya fasten her step even more, hoping to save as many people as she could from her own kind.
"Saya, wait."
Haji tried to follow her pace.
As soon as they came across the abandoned building, they could see many figures fighting the monsters. While they were heading closer to their target, they were able to distinguish four people who were using abnormal ways of dealing with the vampires.
"That's..."
Saya was shocked at the view of a teenage boy floating in the sky as if he could walk on thin air. The flames that surrounded his body stunned her even more.
"Is he.. human?"
Saya wondered whether she should attack the boy as well.
"Please wait here."
Haji disappeared from her sight in an instant and reached the silver haired boy with the dynamites.
"You have to stop this."
The young Guardian panicked at the sudden voice of the stranger who had appeared in front of him out of nowhere.
"Who are you?"
He pointed his dynamites towards the guiltless servant.
"Please stop this. It is not your job and you can't defeat them."
"Are you with that monster? The Vongola Family can defeat any opponent!"
With those words Gokudera threw his dynamites, mistakenly thinking that his enemy was just a regular person. Haji moved extremely fast and with some abrupt movements he had placed himself behind the delusional Storm Guardian and he had wrapped his right arm around his neck, while with his left arm he held his hands tightly, immobilizing him completely.
"You have to stop."
"HEY!"
Gokudera's scream drew Tsuna's attention who was desperately trying to defeat the monsters.
"Gokudera-kun!"
The brunette looked confounded at the stranger.
"Saya, now!"
The immortal girl ran towards the beast with her eyes glittering a bloody red color.
"Hey, stay away! It's dangerous!"
The Sky Guardian looked at the girl troubled and floated towards her to tell her one more time to leave. However, Saya was holding her katana and as she tore her fingertip so that her blood would flow through the slits of her sword, she passed through the mafia boss and fiercely attacked the bloodthirsty creatures. All Guardians gazed in astonishment and awe as the girl split the monsters which were now slowly being petrified. In less than fifteen seconds, all three monsters had been defeated and perished completely. Afterwards, Saya placed her katana back to its sheath and stayed silent, looking at Tsuna.
"Are you a human being?"
"Hiiiek!"
Tsuna who's hyper will flame had extinguished looked at the girl terrified. The Storm Guardian acted quickly by positioning his body in front of his boss and holding his dynamites towards Saya and Haji, ready to attack.
"What do you want from Jyuudaime?"
He shouted angrily to them.
"Jyuudaime..?"
Haji repeated in disbelief. He was trying to understand whether these boys were comrades of the enemy or if they were involved in some kind of inhuman experiments. Since the discovery of the 'Schiff' everything was possible.
"Ma ah~ There is no need to fight now. Since these people defeated the monsters, they are on our side, right?"
Yamamoto broke into the conversation.
"Huh? Shut up you id-"
"Gokudera-kun, Yamamoto-kun is right."
The silver haired boy looked at his boss confused.
"I... I believe that these people have problems even greater than ours. And I think that they do not want to harm us."
The brunette took a step forward and bowed to the strangers.
"We are sorry we intruded into your fight!"
He said loudly with his head down.
"A-ah, g-gomenosai!"
Gokudera followed Tsuna's steps.
"But you defeated them to the extreme!"
Ryohei's extremely loud voice startled the two strangers.
"Mama, mama!"
Unfortunately his loud voice startled Lambo as well, who woke up from his nap.
"Lambo!"
Tsuna ran towards him and hugged him, trying to comfort his uneasiness. Saya and Haji looked surprised at the child.
"A child..."
The girl spelled in awe.
"Why would you bring a child here?"
"Ah, you don't have to worry about Lambo, he is a strong Guardian to the extreme!"
"Onii-san!"
The brunette looked troubled at Ryohei for what he had said. He was sure that the fact that they were members of a mafia family wouldn't have a positive impact to the ones who defeated the monsters.
"Guardian? Is he your slave?"
Saya asked surprised, misinterpreting Ryohei's words.
"Eeh? N-no!"
Tsuna replied confounded.
"It's... well h-he's.. eh..."
The Vongola boss was looking around, trying to think of a believable lie.
"Jyuudaime is the tenth boss of the Vongola Mafia Family! Got a problem with that?"
"G-Gokudera-kun!"
'Ah, he did it again...'
Tsuna was helplessly trying to cover the mafia issue but Gokudera rendered futile that attempt of his.
"Mafia?"
Haji repeated confused.
"You're still kids."
Saya added surprised.
"Well, aren't you young as well? How did you manage to defeat these monsters?"
Yamamoto replied with his usual smile.
"Chiropteran."
Saya responded.
"They are called Chiropteran and they feed off human blood."
"Hiiiek!"
Tsuna screamed terrified.
"L-like v-vampires?"
"No, no Jyuudaime! Vampires are humans who have died and been resurrected by their vampire creator."
Gokudera replied, proud of his knowledge.
'Gokudera's knowledge scares me...'
Tsuna thought dismayed.
"No..."
Saya spelled gloomily.
"Chiropteran are indeed vampires."
She said while looking away. Haji noticed her mood change and hurriedly wrapped his arm around her.
"We must go."
He said and as his master nodded, they both disappeared from the Vongola Family's eyes.
"What the hell..."
Gokudera said bewildered.
"They disappeared!"
Yamamoto added stunned.
Tsuna was looking at the place numb. No words could come out of his mouth. Ryohei took a step forward, raised his fists in front of him and screamed.
"This is confusing TO THE EXTREME!"
"Saya..."
As soon as Saya and her chevalier reached their current residence, her loyal servant uncovered his monstrous hand and slit his palm quietly.
"Haji, I don-"
"Saya, you need this."
The immortal girl stared at Haji as he was approaching her. She couldn't hide the thirst she was feeling as the blood of her Chevalier was dropping on the floor.
"Haji..."
"Please, drink."
With these words he placed his palm in front of her mouth and Saya, hesitant at first, sucked his blood, hoping that she wouldn't ever need it again; even though it was impossible.
"What do you think?"
She suddenly stopped drinking and raised her head, looking at Haji.
"What do you think about them? Who were they?" She asked.
"I do not know."
Haji gazed in her eyes.
"Do you think they were enemies?"
"No."
He replied certain of his answer.
"E... experiments?"
"Maybe."
Saya sighed troubled at his response. They were aware of the experiments that were made to turn people into Chiropteran and they had already met the Schiff whose members all had a tragic ending. Nonetheless, the people they had just encountered, they... they were merely kids.
"When is this gonna stop?"
She shouted angrily for this world's cruelty, yet she already knew the answer. She would be the one to put an end to it; she would be this world's savior if she could just murder her own sister.