Disclaimer: Sora no Otoshimono and Casshern Sins are respectively owned by Suu Minazuki and Yasuko Kobayashi in collaboration with Madhouse, not by me. This is being done purely for fun, constructive criticism is welcome and flames will be ignored.

A special recognition and thanks go to The Infamous Man and Lucas Bane, betareaders and co-founders of this fanfic.

Heaven of Sinners

Prologue - The Awakening

"In the beginning God created the heaven and the earth."

Genesis 1:1

Synapse. This is the name of the "Heaven" since times immemorial hidden in the sky of the planet Earth. Composed of a multitude of massive, floating islands and blessed with amazing technology centuries beyond anything possessed by the humans on the surface, it is the house of a race of beings similar in appearance to humans but gifted with wings capable of making them fly like birds: the Angels.

In this utopian place no one needs to work to sustain themselves and their family and, thanks to the medical advancements, aging and illness are completely unknown. With nothing else to do nowadays the Angels spend all their time "dreaming" inside particular machines that created human-shaped bodies on Earth and, like an avatar, allowed them to live lives as human beings.

With all the denizens asleep, the duty to maintain Synapse fell onto the Angeloids: androids modeled after the Angels. They worked as both caretakers and living weapons for the Synapse. They select their master through a process called Imprinting by means of a chain wrapped around the master's hand connected to a collar around the Angeloid's neck, symbolizing the master-servant relationship. One shinning example is Ikaros, the "Uranus Queen", First Generation Strategic Battle-Class: Type-Alpha Angeloid, the masterpiece of the genius researcher Daidalos. This mighty weapon in the form of a beautiful girl once, by order of Synapse, single-handedly destroyed the Tower of Babel, a massive tower built by the Downers (how Synapse calls the humans) along with the city around it and all its inhabitants. The mere idea that the Downers thought themselves worthy and arrogant enough to try to reach Heaven prompted the Council of Synapse to send Ikaros to wipe them out.

However this is the past. The modern days are troubled times. At the top of the central and larger island of Synapse, sitting on the throne inside his temple, Reikoku, the Sky Master and absolute leader of Synapse, was seething with rage and uneasiness. Dressed with an ancient Greek toga and sporting immaculate long blonde hair which hid his eyes in shadow. He was the only Angels always awake: on him lies the duty to maintain the status-quo of Synapse and the right to do as his please with all the floating world's possessions, including Angeloids.

It all began when Daidalos turned traitor and sent Ikaros with her memories and abilities sealed on Earth before going in hiding somewhere on Synapse. On the surface the Angeloid proceeded to bond with a human teenager named Tomoki Sakurai, who then utilized Ikaros's abilities to do, of all things, incredibly stupid and perverted deeds, like freezing time and walking around naked and making female panties fly like birds.

So upon discovering the exact location of the missing Ikaros the Sky Master ordered another Angeloid, First Generation Electronic Warfare-Class: Type-Beta Nymph, to retrieve her, but under the pressure Alpha awoke once again as the "Uranus Queen" and pushed Nymph back to Synapse. Further attempts to either recover or destroy Ikaros, including using Beta herself as a bomb, ended in failure and the subsequent defect of Nymph after the humans Tomoki and his friends broke the Angeloid's imprinting.

To add insult to injury one of the Downers called Eishirou Sugata, an obsessed weirdo with a genius intellect, with the help of Beta began to travel to Synapse through the "Dream Dive Game", a system to enter another dreams, after it was discovered Sakurai's dreams are mysteriously connected with Synapse. As of today no matter how much the Harpies sisters, First Generation Interceptor Type, Ambush Class: Type-Gamma, Reikoku's personal guards, struggled, they have yet to succeeded in capturing the intruder.

Reikoku's next move was to send the last original Angeloid, First Generation Close Combat-Class: Type-Delta Astraea to assassinate Sakurai Tomoki. Unfortunately in order to give her the edge in combat her creator Daidalos neglected the development of her processing power, thus making her incredibly clumsy and prone to fail due to simple mistakes.

Running out of patience the Sky Master decided to jumpstart a new project: the Second Generation Angeloids, theoretically surpassing the First Generation by a large margin. While a skilled researched himself the Master of Synapse was still inferior to Daidalos's prowess, but assured himself the millennia's technological advancements since the creation of the First would give him all the advantages he needed.

The first prototype, Evolution-Class: Type-Epsilon Chaos, while inexperienced and a little unstable was capable of defeating all the enemy Angeloids, even Astraea who in the middle of combat declared she has fallen in love with Sakurai and even broke her Chain of Command with her own hands. Only Ikaros' near-suicide plan to dive with Chaos into the ocean transformed a crushing defeat into a victory: Angeloids can't swim because their wings absorbed water, so if one fall into the sea it will go down to the bottom and being unable to leave. Reikoku was of course disappointed, but consoled himself with the assurance it was only a matter of time before Chaos reached a coastline and resumed her mission.

So to amuse himself in the meantime he watched as Tomoki befriended Hiyori Kazane ,a girl who in reality was an Angel dreaming of being a human. When a car incident destroyed her avatar, removing all memories of her existence as a Downer (except the Angeloids and Tomoki), he decided to grant her plea to continue her dream. But he did so in his own way: he turned her into an Angeloid, Second Generation Weather Control-Class: Type-Zeta, and send her to destroy Ikaros and the other Angeloids, assured that they would not dare to attack a friend. He also gave her more sophisticated hacking abilities than Nymph to be sure they could not snap the mind control.

But Nymph in a moment of desperation activated "Pandora": also know as the "Self-Evolution Program", it allows oneself to grow in power through time and the absorption of other things. With it Beta's hacking abilities evolved and gave rise to a new skill dubbed "Aphrodite" capable of breaking Hiyori's enslavement.

While an unexpected development the Sky Master was still confident Chaos would still win once she returned, since she too was equipped with the program "Pandora".

That's why his mouth dropped in shock when, after a battle with Chaos's new adult form, he witnessed another betrayal, with Chaos deciding she 'liked' Tomoki and the Downer using a padlock-shaped device to shut off all forms of communications and control between him and the Angeloid.

Fooled. Again. For the umpteenth time a mere perverted, middle-scholar, human managed to play him for a fool. Hardly a foe worthy of being called such. And yet now the stupid Downer could boast the alliance of no less than five of the most powerful Angeloids. Well, in truth they were six if you also count the one First Generation Medical Specialist Angeloid Oregano, which once followed the Downer Sugata to Earth in one of his expeditions. But her battle strength was nonexistent and apart for her medical skill it was no threat. Oh, and let's not forget about the assistance of Daidalos in person!

"Why..." He growled with gritted teeth, staring at the giant holographic screen displaying a replay of Chaos's second battle. "Why I can't win against him!"

His hand slowly twitched into a claw-like pose, his fingernails grating against the marble of his armrest and leaving noticeable traits on the otherwise pristine surface.

"Two years. For two entire years this farce has gone on! I, the Master of Synapse, outclassed by an insignificant Downer not even into his adulthood yet. My most powerful Angeloids now against me! That Sugata treating Synapse as his study camp! And Daidalos...even if I destroy her hideout now that I saw her teleporting, who knows how many more spare hiding places she set beforehand?"

His other hand reached up and typed a command on an intangible keyboard and the video on the screen shifted to a picture of a pink haired girl with bright emerald eyes, two small pods on her ears and a collar with a short chain around her neck.

"Uranus Queen. This is all your fault. The other trash have all weakness I can exploit, but you...you are the only one with too much power. The "Variable Wing Core" and long-ranged, target-searching attacks...what a dreadful combination. And that Tomoki with his absurd ability to turn enemies into allies. How in Synapse he is doing it? And why I can't doing the same?"

He kept contemplating while gazing at the image of the most powerful weapon of Synapse. 'I need something. Something capable of defeating the Uranus Queen and resisting the Downer's persuasions. Another Second Generation, this time more than one? The result will probably be the same. A new anti-air defense to target them directly from Synapse? Destroy them all in one shot is not assured and I run the risk of activating the "Pandora" inside the Uranus Queen, and that will be beyond bad. What? What I know that can stand Type-Alpha? A weapon so great it has no equal...'

Fire. Fire everywhere. Buildings crumbling. The once blue sky covered with smoke and ash. Cries of pain and pleas for salvation filled the air. The bodies of countless Angels littered the landscape, their bodies mangled beyond recognition. Blood. Blood everywhere.

Reikoku put a hand over his mouth and forced back the retches threatening to overcome his body. Blood drained from his face while cold sweat began to appear on his skin.

A male Angel screaming in pain and fear while his innards are mercilessly ripped out of his belly, the hideous and brutal act of butchery continuing until his screams stopped. Only for a second Angel to suffer the same fate after not even one second has passed. This time his wings were sundered first.

And amidst the chaos and devastation a pair of soulless orbs of glowing white light stared at him, looking directly at the depths of his soul. Judging.

And finding him unworthy of living.

"What the Hell I am thinking?!" He growled under his breath, forcing his respiratory system to slow down to a normal pace. "If I do that, forget about the Uranus Queen: the entire Synapse will be reduced to a smoking wrench before the Earth suffered the same fate!"

He paused, as if considering carefully what he did just said. Then in a sudden change of mood he laughed, a cruel sound with an hint of bitterness. "Yeah right, as if I even give a damn about the Downers! And since when do I care for this boring place I call 'home'? In the best case that damn Tomoki will cease to be a problem. In the worst Synapse will be plunged into unprecedented disorder."

He cruelly sneered. "A win-win situation. Time to remind all the worthless wenchs what fear is really like. Harpies!" He called, and with a flutter of wings his most trusted subordinates appeared before him. The two Interceptor units were twins, with the only difference being the hair's colour: the older sister had light brown hair while the younger one had green hair.

They both bowed and asked in unison. "Yes, Master. What are your orders?"

"Follow me." He replied while rising from his throne. "For my next move against the Downers I first need to recover a certain 'something' from an underground level."

"Yes master." They repeated while faithfully following after their Master. "Excuse me, Master." The younger sister asked, "To what level we need to go?"

"The B-66." He answered simply

"I see, the B-Sixty...six..." They stopped in their track, realization drowning on them. The next moment... "THE SIXTY SIX?!" They both screamed.

Reikoku turned his head and quirked an eyebrow seeing the sisters white as a sheet and trembling.

"F-f-forgive me M-Master, b-but isn't the s-sixty-six t-t-that..." The elder stuttered, before gulping and continuing. "That...infamous place?"

"Yeah! T-t-the...Gehenna?" Pressed on the younger, whispering the last word as if the mere name was enough to invoke terrible divine wrath.

The Sky Master smiled. 'So, after all this time it is feared as much as the beginning.' "That's right." He replied, enjoying the discomfort of the two.

"WHAAATT!" They shrieked with terror, stepping back and sweating profusely. "Why do you want to go there? That place is cursed, Master, cursed I tell you! Everyone who go near is killed on sight!" Screamed the elder Harpy.

"I-I heard that inside is sealed a monstrous mechanical Angeloid-eating beast of untold ferocity! It is so strong that the Uranus Queen was built with the precise purpose of blowing it up with all of Synapse if it even broke free!" Said the younger.

"The rumors said that inside its database rest a super lethal cybernetic virus capable of infecting Angels and Angeloids alike: first they lose their sanity and then their bodies putrefy!" Continued the older.

The Sky Master wanted to burst out laughing. What kind of silly stories the Angeloids told each others?

The younger Harpy spoke again, a slight blush on her cheeks. "I also heard it contain a lot of embarrassing photos of Master, like when he was a baby an need to change the diaper."

A loud Crash! can be heard following the Skymaster bashing his head, hard, on the floor. He rose up and roared. "WHAT!?"

Realizing her mistake she quickly tried to cover her blunder. "Nothing! Absolutely nothing! Don't worry about what I say Master. I'm stupid so I say some nonsense from time to time." She tapped the side of her head to enforce the impression of airheadness.

The Master briefly contemplated burning down the district where those stories originated from, before deciding such things were unworthy of his efforts. He resumed walking toward the central elevator. "If you want to know there is something sealed there, and it's as dangerous as those silly stories said." He sneered. "One way the people called it in the past is the "Angel of Death". Fitting I say."

The two Harpies shivered at the ominous title before the elder asked. "M-master? What we are going to do?"

He laughed. "Why, we are going to free it!"

For the first time in their long life the Harpies contemplated the unspeakable thought of disobeying their master's orders, so great was their fear for the task they were called to perform. In the end loyalty won and they hurried after their liege.

Praying they were going to live long enough to see the sun rising from the horizon the next morning.

The ride in the elevator was uneventful save for the sisters ever increasing sweating. Even Reikoku was silent, his distant eyes contemplating something only he could see. Then with a soft noise the doors opened and the three found themselves at the beginning of a cold and badly illuminated hallway, the end hidden behind a veil of fathomless shadows. Wordlessly the Sky Master ventured into the darkness, the two Angeloids hot on his trail.

"Ehi, Nee-san." Whispered the younger Harpy to her sister. "If it's as dangerous as the Master said, why are we...?"

"He said it is to fight the Downers." Whispered back the older sister. "So whatever the hell is down here the Master must think it can stand against the Uranus Queen. She is the most powerful of the traitors."

"You're right. Hey, Master…" She replied raising her voice. "Can this "Angel of Death" stand against Alpha?"

He shrugged. "Honestly? I can't imagine something capable of destroying it for good. Not even the firepower of the Uranus Queen."

"But, but then what will we do if you're in danger, Master?" Asked the older.

"Obviously I expect you two to hold it back while I sealed it again. Can't see you last more than five seconds, but it should be plenty of time to do it." He answered nonchalantly.

For the second time in both the day and their life the Harpies seriously considered running away with the metaphorical tail between their legs and search for a better employer.

Eventually after a long walk and several drops in temperature they reached a massive steel door, all black save for a simple white square in the middle. Red writings in the ancient language of Synapse where inscribed all over its surface and the adjacent walls. Looking closer the elder sister saw they were all the same phrase: 'Don't open'.

"Warning." A mechanical voice suddenly spoke, startling the sisters. "You are entering an area classified under the threat level Dogma First White: "FALLEN". Approach is forbidden to all but the members of the High Council of Synapse. Identify yourself. Failure of belonging under the required parameters will result in immediate disintegration. I repeat: identify yourself."

"My name Reikoku, first Head of the High Council of Synapse, crowned with the title 'Sky Master'!" The Angel declared loudly putting one hand on the white square. At the contact it began to glow. "Identification Code: Y-80065-H-39467-W-22118-H-0001. By the power bestowed upon me I order the release of the seal!"

"Identification Code Accepted. Scanning...Blood pressure: check...Blood type: check...Heart-rate: check...Age: check...DNA: Check. Welcome Master, have a good day." The voice intoned before the massive door split into two and began to sliding open, releasing a gust of chilling air.

"Master, do you want one of us to go back and fetch a coat?" The Harpies asked after seeing their Master shivering in such light clothing. Being Angeloids, they were shielded against the changes in temperature, but their Master was not.

"I am fine!" He shouted back without turning. "If I can't endure this much I have no business being here." With those words he stepped inside.

What greeted them was a bare chamber devoid of any decors, stale air typical of interiors closed for years. The only thing inside was a containment pod in the center: it was white, modeled like a coffin with beveled angles. Two triangular protrusions emerged from its side, the two sisters recognizing them as the space for the wings of the occupant. A blue semi-sphere glowed at the top of the construct. Reikoku crouched down and touched the orb, bringing up an holographic display with various data. Reading it he frowned.

"You son of a bitch. I bathed you in liquid nitrogen, left you rotting here for seven thousands years, and yet you're still as good as the day you were born. Fucking monster."

The Harpies eyes widened: never they have heard their Master use this kind of language. Just what was inside the pod to provoke such a reaction?

"Come on, pick it up so we can leave." He commanded. Nodding they each took one end of the coffin and lift. Surprisingly, it wasn't that heavy.

Half an hour later they were back inside the temple of the Sky Master. Flanked by the two nervous Angeloids with their "Prometheus" rifles draw and ready to fire in case of danger The Master was completing the opening of the pod.

"Vital Signs: ready. Brain waves... increasing. Good, he's waking up. Get ready you two, but don't startle or attack him if he isn't attacking first. There is my life at the stake here." He reminded them.

"Yes, Master" They replied in unison, idly wondering: 'He?'

A final input on the screen and the orb ceased to glow before the upper part of the coffin vanished into bits of digital compressed matter. Intrigued the Harpies leaned forward to see better and gasped.

Resting supine on the inside was a young man dressed in a white one-piece suit with black lines from head to toe, a blood red and stylized 'C' on his chest and two gun-like devices on his waist. Their eyes widened at the sight of six wings the color of the night sky emerging from his back.

'An Archangel?!' They thought. Most Angels have only two wings while some has four. But it said every thousand years an Angel with six wings is born, extraordinary individuals gifted with amazing talents. Not even Angeloids who are constructed are permitted to have more than two wings. But those were all stories: no one has ever seen an Archangel since immemorial time. At least until now.

Their eyes drifted to his head: what greeted them was a handsome face framed with fluffy brown hair. A minute twitching of the facial muscles and the stranger slowly opened his eyelids, revealing deep and soulful blue eyes. He blinked a few times before turning toward a smiling Reikoku with an inquisitive expression.

"Welcome back to the word of the living...

…Casshern."