Disclaimer: All characters from Naruto and Yu Yu Hakusho belong to Masashi Kishimoto and Yoshihiro Togashi respectively.

Prologue

He was exhausted.

It wasn't something that he admitted very often. He was so used to going non-stop that he barely even noticed anymore. Really, he liked it that way. It took his mind off of…things. But right now, all he wanted to do was collapse in his bed and sleep well into the next day. School be damned.

"Sasuke-kun~!"

Apparently the universe had different plans.

Sasuke Uchiha didn't bother getting up from his face down position on his comforter. Merely turning his head towards the window beside his bed, one eye cracked open to give a deadpanned stare at the visitor hovering outside.

"What do you want?" His voice was as flat as his facial expression.

Botan, one of the many grim reapers to the Spirit world, smiled brightly at him from her place on her oar. Despite his always less than enthusiastic responses to her appearances, she knew on some level they could be considered friends. One of the few friends Sasuke had. However, she was sure he would rather cut off his own hand than ever admit that.

"Sorry to interrupt your afternoon nap, but Koenma has a new case for you!"

Sasuke's lips curled into a scowl that was more directed to his 'boss' than Botan. He had just finished recovering an item for Koenma not even 12 hours ago and already the Prince of the Spirit World was assigning him something new. He was an absolute slave driver that cared for little else than saving his own ass. The dark haired boy shut both eyes and turned his head in the opposite direction of his window, his brows creased into a small frown indicting his obvious displeasure.

"I pass. Get Naruto or Sakura to do it."

Naruto and Sakura were the other two spirit detectives. Sometimes they performed as a team, sometimes separately. They were loud and annoying, but were at least competent. Naruto, a fox demon who worked out some kind of deal with Koenma to take residence in the human world to start a new life, was always surprising him with his ever growing strength. When they had first met, Sasuke could easily beat Naruto without breaking a sweat. Now, Naruto was on par with Sasuke, and their brawls often ended in a stalemate with damage to both sides.

Sakura was a human psychic with immense spiritual energy and control. She was able to translate it into brute strength, but more importantly she was a healer. The best that had ever been seen. There had been many times that if Sakura wasn't on their side, Sasuke was positive he or Naruto, maybe even both, would have died.

Botan placed a finger on her chin and her eyes rolled up to the sky in thought.

"Well I would…but Koenma already sent them on a different assignment. That just leaves you."

Of course it did. Heavens forbid that Sasuke ever get a break. Releasing a highly annoyed sigh, Sasuke rolled onto his back and finally sat up. He ran one hand through his hair while the other reached out towards Botan.

"Fine. Hand it over."

Botan looked confused for a moment before realizing what he was asking. She fumbled in her robes for a moment before pulling out a black video tape out of the sleeve of her kimono. Flying a little closer to the window, she dropped the tape into the boy's outstretched hand.

"It's a pretty straight forward mission. He said it was something you should be able to handle easily."

Sasuke resisted the urge to roll his eyes. Somehow these 'easy' missions always turned out to be much more than they seemed. He lifted off his bed and headed towards the dual DVD/VHS player and TV across his room. Kneeling down he pushed the tape in and switched on his TV.

"Would it kill him to upgrade to DVDs…" He mumbled. He was still a little confused on the outdated technology the spirit world sometimes used.

He heard Botan settle on his bed, probably deeming it safe enough to enter now that he was actually up and had accepted the mission. His eyes focused on the TV screen as it flicked on, Koenma's toddler form popping up on the screen.

"Sorry to send you on another mission so soon Sasuke, but while this mission should be simple it does need immediate attention."

Another picture, this time of a girl with long black hair and the oddest eyes he'd ever seen, popped up. In a conventional sense she was pretty, nothing particularly stood out about her besides her eyes. They were completely white. No pupils, no color, nothing. It was slightly creepy to be honest. Her facial expression was soft with hints of sadness lingering beneath. There was something in her expression that he could relate to…Before he could analyze the picture further; Koenma's voice went into a brief explanation.

"This is Hinata of the Hyuuga. The Hyuuga are a highly structural group of demons. They do not behave like normal demons. They act more like a clan with their own rules, regulations, and means of operating. As you can see from the picture, all Hyuuga have eyes like Hinata. It is a rare ability called Byakugan that gives them penetrating sight and telescopic vision. This allows them to see internal energy circulation system in other beings. It also grants them with a near 360° view."

Well that was interesting. He had never heard of a ability like that before, in human nor demon.

"What makes them even more so fearsome is their fighting style called Gentle fist, with it they are able to cut off use of energy and cause internal damage. They are a feared and envied group of demons. Because of these special eyes, they are the targets of many, demons and humans alike that want to try and utilize it for themselves. Hinata here is an important member of the Hyuuga, their leader's daughter…and she's been kidnapped."

Sasuke's brows and corners of his mouth came down. He couldn't understand that if the Hyuuga were such a formidable group of demons, how was someone able to kidnap a member of their group. Furthermore, the girl should have been able to take care of herself. That meant his opponent was going to either be very powerful or had something to their advantage.

"We believe a group of human psychics who are simply known as 'Kumo' are the ones responsible. It can only be assumed they want Hinata for her eyes. Many try to take the Hyuuga eyes and implant it within themselves to be granted the same abilities. Your mission is simple. Find the girl, return her to the Hyuuga. It would not end well for any world should the Hyuuga become desperate."

He went on to explain the location of the group, what to expect, and the time in which the mission was to be complete. 5 days. 5 freakin days to find a missing person, possibly defeat a group of psychics, and return to the girl to the demon world.

Sasuke decided he needed to buy a dictionary for Koenma because obviously the toddler didn't know the definition of 'easy'.

The compound was exactly where Spirit World intelligence said it would be. At least they got that right. Sasuke crouched on a tree branch a few feet from the building. The entire place was in the middle of a forest, well away from civilization. If he hadn't been left a hefty sum of money from his family he would have bitched about the train and bus fare it took to get there…Maybe he still would, just to get under Koenma's skin.

It was almost like a village. Some large buildings, some small, most were interconnecting but all surrounded a large empty court yard in the middle. He assumed that's where they trained. He had been watching the place for about 3 hours. His spirit energy had been suppressed to avoid detection. The dark haired boy always preferred to observe a place before just rushing in, unlike his two impatient teammates. He always liked to be able to make a plan for every possible outcome.

The place was crawling with psychics. He could already tell that at least one fight was going to be inevitable. Hopefully it wouldn't escalate into a fight with the entire compound. It wasn't that he wasn't confident in his abilities, he couldn't remember the last time he had been defeated, but there was power in numbers and all it would take was a moment slip due to exhaustion and someone could get a lucky shot in.

"Always think before acting little brother."

The voice drifted into his mind, a whisper from the past. Sasuke shook his head to scatter the memories that threatened to follow. Memories he desperately wanted to forget but never could allow himself to. It had been seven years since that event. The day that changed his life forever and put him on the path he was now. Without that, he wouldn't even be a spirit detective right now. He'd be a normal boy, his only concerns being school & fighting off his fan club. Maybe he'd be involved in sports or a club. He'd be able to laugh and smile easily. Now his life was consumed with achieving one goal.

The death of his brother.

Sasuke couldn't help the scowl that marred his handsome features. Now was not the time to think about that. He didn't need any distractions during his infiltration. There was a fluttering beside him before a weight landed gently on his shoulder. His eyes cut to his right, meeting the gaze of a small hawk. He supposed it could be consider that he had some kind of contract with it. It served him when he needed, he was able to summon it at any time, and in exchange he provided it with spiritual energy from time to time. In a silent exchange between them, he was able to decipher the Hyuuga was being kept in one of the inner rooms of the compound. There wasn't heavy guarding, which seemed odd, or maybe they were just cocky.

"I hope it's warranted" he thought, a smirk curling the end of his lips.

With the information he needed, Sasuke jumped off the tree branch and began to make his way into the compound.

So far so good.

He had managed to avoid confrontation with any of the Kumo psychics so far, and if what his Hawk had told him was accurate he was getting closer to the location of the Hyuuga. Sasuke gently pressed his back against a wall. He only needed to round the corner next to him to be in the hall with the room the Hyuuga was kept in. Preparing himself for the possibility of an enemy around the corner, he pushed off the wall and moved in a defensive position.

It happened quickly. He dropped to the floor in a duck as a pale hand came charging to his chest, his reflexes were faster than his attacker and he was able to swing his leg out to swipe the feet of the other from underneath them. Rather than falling to the ground like he expected, they recovered gracefully arching into a back flip springing off their hands back on their feet. Sasuke didn't give them a chance to make another move. He charged with his fist as his side, flashes of spirit energy crackled around his arm, producing a sound reminiscent of many birds chirping. He blinked and suddenly his eyes had changed from ebony to blood-red, black tomoes swirling in anticipation of his next attack. His arm pulled back ready to deliver the final blow to his opponent.

Then he stopped.

A flattened palm was paused only seconds away from his chest. His chidori was a mere inches away from a round face framed by long dark hair. Red eyes clashed with white. One with recognition, the other filled with wary. Sasuke's chidori slowly died down, the chirping eventually fading away. It was in that moment that he realized exactly who he was fighting.

"Hinata of the Hyuuga."

He had almost killed his assignment. Hinata's eyes narrowed as she scrutinized him. The veins around her eyes were slightly bulged in what he assumed was her Byakugan activated. He wasn't sure what she was trying to find, but he was getting impatient just standing there. One of the Kumo could come across them at any time. After a few seconds, she slowly retracted her palm.

"Y-you…you are not like the others…"

Sasuke gave her a curt nod. Though she had pulled back her attack, her body was like coiled like a spring, ready to react if necessary. He hated explaining himself, but knew he would have to in order to get the demon girl to come with him.

"I'm a Spirit detective. Spirit world has sent me here to take you back to the Hyuuga…" It wasn't until now that he noticed two bodies over Hinata's shoulder, both crumbled to the ground. It appeared that she had managed to defeat a few of her captors already. A small smirk quirked his lips. "But it seems you might not need my help."

Oddly enough a pink hue appeared on Hinata's cheeks, as though she was embarrassed or ashamed of her accomplishment. Her eyes diverted to the ground.

"I didn't kill them," she said softly.

She was completely different from what he was expecting. Really he wasn't sure what he was expecting, but this obviously shy demon was not it. He didn't have time to dwell on it. They were already pushing their luck time wise.

"I don't care. Let's go."

The Uchiha turned on his heel and headed back the way he came. When he didn't hear any steps behind him, he paused at the corner and looked behind him. Hinata stood there with a conflicted look on her face. Her bottom lip being chewed gently between her teeth indicting thought. Sasuke could feel annoyance bubbling up in his chest.

"What are you waiting for!"

"How d-do I know I can trust you?"

He almost wanted to smack his forehead in frustration. His patience in dealing with others was very thin. It wasn't a stretch to say he was a bit socially inept. That was Naruto or Sakura's forte. He usually gave an order, and it was followed, simple as that. Sasuke had to remind himself that the demon girl had just been kidnapped. It was only natural that she was being cautious. So he tried again.

"You can't. But you have two options, stay here and probably get caught again, or come with me and go home. It's your choice. Regardless I'm leaving." And he meant it. Koenma be damned, he couldn't help someone who didn't want to be helped, and he wasn't going to beg.

He turned to back to look around the corner, after deeming it safe he began to make his way back the direction he came in.

This time he heard steps behind him.

"Should've known it was too easy."

They had been so close, so close to getting out of the compound without being discovered. The bodies of the two Kumo psychics that Hinata incapacitated must've been found for now there was a group of ten standing between them and the entrance that they had planned on using to escape. Judging by their spirit energy, he determined that while many of them were powerful, he was better. His only concern was that he could not fight to his full potential if he had to worry about protecting Hinata as well. He didn't need to turn around to feel the uneasiness radiating off her body.

"Hinata."

She made a noise of surprised, her focused shifted from the group around them to her mysterious savior's back.

"Y-yes?"

"You can handle this." He spoke with such conviction. They were virtual strangers but he spoke as though he knew her abilities, what she was capable of.

No one had ever spoken to her like that before.

Hinata's face hardened in determination and her body straightened.

"Yes."

"Hn. Let's finish this quickly."

With that a now familiar chirping filling the air, Sasuke's spirit energy began to rise. He made the first move, pushing off the ground with speed rarely seen and rushed forward meeting one of the Kumo psychics head on. In the background he heard Hinata cry out "Byakugan!"

The Kumo psychics was caught off guard by his speed and within a few minutes three of them laid upon the ground blood staining the wood from the open wounds in their chest. Sasuke's face was covered with flecks of blood only adding to the intensity of his red gaze. The other Kumo psychics proceeded with caution now, some fearful. They circled him, gauging his reactions when one chose to feign an attack. He was never caught off guard though, his body language never revealing anything. A cocky smirked crossed his features and his hand opened and closed twice in a 'come on' gesture. Feeling insulted, the Kumo psychics began their group attack on the young boy.

They didn't stand a chance. His skills coupled with his bloodlust caused him to make quick work of them. A light sheen covered his forehead from the work but there was no other indication that he had struggled at all. Now three more bodies lied at his feet. Sasuke turned his attention to Hinata who was currently dealing with two of the remaining Kumo psychics. Two others were scattered a ways from her. The only sign that they had been attacked was many dark bruised marking spread across their bodies.

She looked exhausted, her breathing was heavy and already there were a few bruises littering her arms and face. Sasuke merely watched at first, partly curious about the abilities of the Hyuuga. Again the veins were bulged around her eyes. It gave her imposing look that her normally withdrawn demeanor lacked. Her body was crouched in an unfamiliar fighting form, arms raised with palms flat.

One of the Kumo psychics charged at her head on. He suddenly split into three causing Sasuke's eyebrows to rise in surprise. He had never seen a technique like that before. His eyes greedily copied the move, already learning the mechanics for it and tucking it away in his mind for future use. Hinata didn't look deterred, the determination even more prominent on her face. Sasuke tensed as the Psychic and his three clones drew closer, he made move to intervene when Hinata's demon energy began to pore out of her body.

"Hakkeshō Kaiten!"

Hinata began to rapidly spin. A burst of energy forming a dome surrounded her impacting against the Kumo psychic and his clones thrusting them back causing the bodies to crash into the wall. Two of the bodies disappeared in clouds of smoke while the other remained still on the ground. Hinata rotating body came to a slow then halted, her breathing even heavier now and her legs shaking beneath her. It was obvious she was at her limit. At that moment the crackling of lightening made itself known in the now quiet air. Hinata had forgotten about the other Kumo psychic.

The Hyuuga turned around as quickly as she could in her current state but still wasn't fast enough to intercept the attack. She closed her eyes to brace herself for the inevitable pain but it never came.

The Kumo psychic's eyes were wide in horror. His body was frozen in its attacking position. A sword formed of spirit energy, with what appeared to be to lightening curling around it, was positioned ready to strike only mere inches from Hinata's head. Hinata slowly opened her eyes, curious to why the blow never came. White eyes widened as her sight was filled with Sasuke's black clad back. When had he managed to come between them?

Suddenly the psychic crumbled to his knees at Sasuke's feet, the spirit energy sword dissipated from his arm. All the color was drained from his face, his eyes remained wide staring at seemingly nothing.

"Hmph. I thought the Byakugan gave you 360 degree vision, " Sasuke's voice cut through the slice.

Hinata's shoulder slumped, feeling almost useless compared to the young human who was able to take down the psychic so easily.

"T-There's a blind spot…few people know about it. They did. That's how they w-were able to capture me... I'm sorry"

A look of surprise crossed the Hyuuga's face as a hand was placed on top her head. Sasuke didn't look her while he made his clumsy attempt to comfort her. He didn't know why, usually he didn't give a damn. Maybe it was because he actually was impressed and slightly respected some of the skill she displayed.

"You took down six psychics today even though they knew your major weakness. There is nothing to apologize for."

It wasn't much, but it was all he had to offer. That seemed to be enough Hinata, for it caused her face to split into a genuine warm smile, a blush tinting her cheeks. He had never known someone to be so pleased with the simplest things.

Awkwardly he removed his hand from her head and allowed it to drop back to his side. Sasuke briskly turned away from the Hyuuga demon and began to head towards the exit.

"We should go before others come."

Hinata stumbled after him, still a little weak from using so much energy, but managed to catch up beside him. Briefly she spared a glance at the man still sitting at the floor as though in his own little world.

"What d-did you do to him?" She inquired softly.

"I used my Sharingan."

"S-sharingan?"

"It's an eye technique I utilize by channeling my spirit energy. It gives me a number of abilities…Similar to your Byakugan I suppose. He'll be stuck in an illusion for maybe a few days, weeks, maybe years… I don't care." He gave her the best explanation he could without revealing too much. Although he didn't have anything against the Hyuuga, that didn't mean he trusted her. Too much information given away could lead to trouble in the future.

"I didn't know humans could be so…amazing," He would've felt insulted if she hadn't said it with such awe.

He chose not to respond.

"Bingo, bingo bingo! I knew you'd get the job done Sasuke-kun! Why Hinata you're much prettier than I imagined!"

Botan had taken an immediate liking to Hinata. She gushed over the girl as though she was a new doll, something Sasuke wasn't sure how Hinata tolerated. All she did was give Botan a soft smile, her face red from embarrassment and poking her fingers together, a habit he failed to notice before.

Sasuke watched the two females interact from his place underneath a shaded tree. His back propped against the trunk, one knee drawn up to his chest. A group of three workers from the Spirit world were concentrating their energy to open a portal to the demon world to allow Hinata to pass.

She certainly didn't SEEM like a demon, especially one capable as being as powerful as Koenma expressed. In fact if it weren't for her eyes, she could very well pass for human. How such a demure demon survived in the world she lived in was mind bogglingly. Most of the demons he had come in contact with were ruthless. Naruto had once confirmed that living in the demon world was not for the weak of heart.

"There's more to her than meets the eye..." He briefly thought.

"U-Uchiha-san?"

Sasuke snapped away from his musing, his gaze drifted to his left to see Hinata who was now sitting on her knees beside him. He noted that she wasn't in his personal space, close enough to talk but far enough to be polite. Something he wasn't used to from the opposite sex. His head inclined towards her slightly, indicating to her he was listening.

"I…um…I just wanted t-to say thank you. I-I wouldn't have been able to e-escape without your help…s-so thank you for your kindness."

"Kindness had nothing to do with it. It was just a mission," he responded bluntly. He wasn't going to sugar coat it like he went to save her out of the kindness of his heart.

Hinata didn't seem off-put by his response. A gentle smile still graced her lips.

"Even so…I appreciate it. I-I hope to repay you one day."

Sasuke shrugged nonchalantly, his eyes drifting close.

"Hn. You don't owe me anything. Just don't let yourself get in the same position again."

"I won't. I'm going to w-work to get stronger. I-I will be able to handle my o-own."

Although her voice wavered in slight stutter, the assurance in her voice was loud and clear. It made his respect for her grow, if just a little bit.

"Hiinnaaatttaaa-chan! The portal is ready! It's time to go home!"

He heard the shuffling of grass which he assumed was Hinata going to her feet. She made a few steps away from him, and then paused. There was a moment of silence and he almost felt curious to open an eye to what she was doing. He didn't have to wait long though before Hinata spoke once more.

"Take care, Uchiha-san."

"…Take care."

"Turns out the item wasn't stolen after all, Koenma just lost it! Can you believe that!?"

Sasuke rolled his eyes, wondering why his loud teammate couldn't just tell a story like a normal person. Why he allowed the two over to his apartment was beyond him. It wasn't like he invited them, they just usually barged their way. He found it easier to just let them do what they wanted and ignore them rather than fight them.

"Sounds like typical Koenma," Sasuke muttered, not looking up from the book he had been immersed in before his teammate's arrival.

Before Naruto could continue his rant, there was a light tapping at Sasuke's window. Sakura chose to open it as Sasuke had made a habit of ignoring everything around him when he didn't want to be bothered. She took a step back as Botan flew into the room, allowing her oar to disappear she dropped to the ground. Sakura smiled at Botan, offering her a light hug.

"Botan! What brings you here?"

"Koenma better not be sending us on another wild goose chase!" Naruto interjected before Botan could speak. Sakura's eye twitched, her fist jutted forward crushing against his cheek.

"Let her speak idiot!"

"Sakura-channnn" Naruto wined, gingerly holding his face.

Botan gave a nervous laugh, always cautious to come in between Naruto and Sakura when they started.

"Botan."

The grim reaper turned her attention towards the more serious team member. He looked at her expectantly with a lifted brow.

"Oh! These…these invitations were sent to Koenma for you three. Here!"

Naruto and Sakura stopped their bickering at that, both looking extremely curious as they were all handed small white envelopes. The only thing written on the outside of the envelopes was their names. Simultaneously they opened their letters and a silence fell upon the room as they began to read it. Sasuke's eyes narrowed as his gaze ran across the words printed on the paper.

"Team Uchiha, you are cordially invited to participate in the Dark Tournament. You and a team of up to five members will be allowed a great opportunity to obtain whatever your heart desires. The tournament will be held at the end of the month, on Hanging Neck Island. Please prepare accordingly. We look forward to seeing you there."

All the letters read the same thing, but at the bottom of Sasuke's letter was a sentence written in hand with a very familiar style.

It is time we meet again, little brother.

The letter was crushed in hand. He couldn't even hear Naruto complaining about being called Team Uchiha when 'Team Uzumaki sounds so much cooler!" or Sakura expressing her concerns over such a sudden invitation. His entire focus was on that last sentence.

"-uke…Sasuke-kun!" Sakura's voice finally broke through his thoughts and his head jerked up towards her. Her emerald eyes swam with worry. She had picked up on his dramatic change of mood. "What do you think, Sasuke-kun?"

"We're going." It was final. They didn't need to know the details of why.

While Sakura appeared concern, Naruto jumped to his feet. His fist pumped in the air, excitement written clearly across his face.

"I can't wait to get out there and show off my skill! Heart's desire huh…? Gonna have to think about what I want, you think they can get Sakura to date me?" The last part was more said to himself but it still caused Sakura to feed him her fist.

"You're so simple-minded Naruto!"

Sasuke took to ignoring his teammates as he contemplated the tournament. Intense training was going to be needed. He needed to be in top form if he was going to get the opportunity to go up against his brother. They could have a team up to five members…while Sasuke believed that he and his teammates were more than powerful enough to handle whatever was thrown at them. It wouldn't hurt to have a little…insurance. They would need to find one or two more teammates.

For a moment white-eyes flashed across his mind.

"Botan."

Botan turned her attention from the bickering Naruto and Sakura towards Sasuke. She was a bit taken aback by the intensity in his gaze. It was almost enough to send a chill down her spine. She had only seen him look like that a hand full of times, it never lead to anything good.

"Yes?"

"Take me to Koenma."

That increased her concern and interest. Sasuke NEVER requested to see Koenma unless it was for something important. She gave him a nod and materialized her oar, her actions finally distracted Naruto and Sakura from their pointless argument.

"Where are you going teme!?"

Sasuke settled on the end of Botan's oar, this was one of the reasons he hated going to the Spirit World, it was deeming riding on the back of an oar.

"I'm going to go get our team together. Start training immediately. You're going to need it, especially you Dobe."

Before Naruto could start a fight, Botan shot out through the window rather than deal with more confrontation. Sasuke hung on tightly as they flew towards the Spirit World. Behind Botan, his sharingan flashed darkly reflecting his current emotions.

I'm coming for you Itachi. You better be ready.

Author's Note: So I'm back to writing! Originally this started off as a one-shot for a SasuHina contest but took on a life of its own. It's somewhat a prologue to the real story. I plan on incorporating many things and characters from Naruto and fitting them into the Yu Yu Hakusho world. If this fic is well received, I do have a sequel already in mind. Review! Love to hear you guy's opinions on this idea.