A/N: Hello! I've always enjoyed reading Harry Potter x Naruto crossovers and I've also recently fallen in love with the couple SaiSaku, so I though to bring my love of both together in this fanfic here. This is AU past Itachi's death (cries holding Itachi plushie) and GoF. This is just the prologue so far, but I hope you like it!

Sai, to me is a difficult character to write, but I will try my best to not make him too out of character.

DISCLAIMER: Naruto and characters all belong to Masashi Kishimoto

Rain

Prologue

Haruno Sakura stood patiently outside the Hokage's office as she waited for Tsunade to be ready for her. She cast a short glance to her left at Sai who stood impassively by her side. They had both been training together with Kakashi when a Chuunin arrived with a request to see the Hokage for the both of them. It was odd that Kakashi was not called as well, and to be quite honest Sakura felt a touch uncomfortable being left alone with Sai.

She didn't have anything against him, and he really tried, but he still was very lacking in the social department; every other sentence that came out of his mouth made Sakura want to punch him all the way to Suna. Sakura looked at him again and noticed a few miniscule changes in him since they had first met. He was less pale, but certainly not tanned. They had learned early on that he only burned. He seemed much more relaxed than before when he was always tensed, ready for attack. He felt her eyes on him and looked up smiling at her. Most of his smiles were as fake as ever, but some were genuine, this one seemed to be a cross between the two; true, but slightly uncomfortable.

"Is there something wrong, hag?" He asked, smile never faltering.

Inner Sakura raged while a twitch came to her brow. She willed herself to ignore it and answer him steadily.

"No, I'm just wondering when Tsunade-shishou will call us in," Sakura said.

"Aa," Sai said, smile falling, "We have been waiting quite a while now."

A crash sounded from inside the room and Sakura and Sai exchanged uneasy glances. Even Sai knew not to cross Tsunade in such a mood. Shizune cracked the door open and poked her head out, her hair was slightly ruffled, but she was no worse for wear than that; a good sign that Tsunade wasn't taking out anger on innocent bystanders. Shouting sounded from inside and Shizune winced.

"If you think I'm going to send you two highly ranked shinobi for any less than-!"

"Now, my dear, we can surely work out a reasonable compromise…"

Shizune looked back inside nervously as the voices grew quieter.

"Eto…" She began, "Tsunade-sama will see you now."

She slipped back into the room, leaving the door open and Sakura and Sai swiftly made their way inside. Tsunade sat behind her desk with one hand at her temple and a bottle of sake in the other. Shizune went up next to her and attempted to get her hands on the sake bottle but was thwarted repeatedly in her attempts. These were both normal things to see. What brought quizzical looks to both Sakura and Sai's faces was the man standing in front of the desk with his back to them. From what they saw he had very long grey hair and wore long purple robes and a matching pointed hat. He turned his head and caught sight of them. Sai and Sakura straightened their posture, crossing their arms behind their backs, and removed expression from their faces, leaving only the mask of a perfect shinobi for him to see. It seemed that the old man's beard was as long as the rest of his hair and was tucked into his belt. He had a pair of half-moon glasses over which looked a pair of twinkling blue eyes. They were oddly reminiscent of Naruto's own cobalt eyes and Sakura was hit with a twang of hurt.

He had left her behind again to go off training. Sakura understood, really. After their recent failure to retrieve Sasuke, Naruto once more felt inadequate and pained. Sakura could relate to the feeling well. Sakura's expression turned stony; no matter how strong she got, no matter what she could do, she would always be miles behind her boys. She had accepted this, but it still hurt and it still made her feel weak and useless. Since Naruto left, Kakashi started training with her and Sai after she had asked them to help prepare her for the Jounin exam. Kakashi was pleased to say the least and leapt immediately into grueling training with her. Sakura realized that he was trying to make up his neglect of her in earlier years, and felt a twist in her heart at the thought. With Kakashi and Sai's help Sakura was able to pass the Jounin exam within two months since Naruto had left.

Sakura was broken from her thoughts when Tsunade spoke up.

"Sakura, Sai," She said glancing over at them briefly before returning her gaze to the elderly man in the room, "Meet Albus Dumbledore, your employer for the next ten months."

Shock coursed through Sakura; ten months? Sai voiced her concerns.

"Ten months, Hokage-sama? There are still…" Sai hesitated, eyes shifting to the man for a moment, "certain matters here that have not been resolved, is it truly prudent to send the two of us on such a long mission?"

Tsunade twitched at the challenge of her authority. The boy was quickly falling into the mold of a member of Team Kakashi.

"Yes, ten months," She said crisply, "We expect a rather lengthy lull in… certain activities of certain people, and I don't expect Naruto's return any time very soon."

Still a little uneasy, Sai and Sakura nodded, not wanting to challenge her further. It was true, though, the Akatsuki had lost yet another member; with their numbers dwindling quickly, it may be a while before they recover.

"Perhaps, Dumbledore-san, it would be best if you explained the mission," Tsunade said tersely. It seemed she was still unhappy with whatever compromise had to be made.

"Of course, Hokage-sama," He spoke their language flawlessly; though there was a distinct lilt that neither Sakura nor Sai could quite place. He turned to the two of them, speaking in an amiable tone, "What I request of you is this. I am Headmaster of Hogwarts School of Witchcraft and Wizardry" – a short, disbelieving glance between Sakura and Sai – "and I request protection for my students against a powerful dark wizard, most especially a certain student named Harry Potter. Our own government, the Ministry of Magic, has refused to acknowledge the rise of this wizard and I fear that my students are in danger for their ignorance."

A flash of anger crossed his face.

"Excuse me… Dumbledore-san," Sakura started, "But… Witchcraft and Wizardry?"

The older man chuckled, "Merely a different way of harnessing what you call chakra. Where I am from… chakra coils are not as fully developed so we use the help of what is called a wand to channel the energy into what we call spells. Most people though, have very poorly developed chakra coils and are unable to use their chakra."

"Civilians," Sai supplied.

"Muggles," Dumbledore said, "Not all of them are civilians, and they have their own strengths and armies. But no, they are not a part of the magical society, in fact they have no idea that it exists."

"So… this dark wizard," Sakura said, bringing them back to the topic of the mission, "What should we expect from him?"

"I do not know quite what he will try this year, as it seems to vary from year to year," Dumbledore said with a slight grimace, "But you will need to constantly be on your guard. I am also quite worried about the lengths to which the Ministry will go attempt to keep people from believing that Voldemort has indeed returned. They must not know that I have hired extra protection for my school and therefore you must be undercover as transfer students."

"Returned?" Sakura asked.

"A long story that is perhaps best for the journey to England," Dumbledore said, "All will be explained. Your language and customs are extremely similar to that of the country Japan, and therefore that is where we shall say you are from. Hokage-sama?"

He nodded to Tsunade and she took a swig from her bottle of sake, earning a disapproving glare from Shizune.

"This is classified as an S-Rank mission, but I trust the two of you to make sure it goes without a hitch. The fact that this is undercover is the reason that Kakashi will not be joining you. Although I am sure he could keep up a henge for quite a long time, not even he can do that in his sleep, not to mention holding it for so long would create problems with chakra depletion."

"Ah yes," Dumbledore interrupted, "It seems that the two of you could easily pass for students at my school, but perhaps I could have your ages?"

"Fifteen, sir," Sakura said, "Soon to be sixteen."

"Seventeen," Sai replied as well, "How could we possibly 'easily' pass for academy students? We do not look twelve."

Dumbledore seemed a bit shocked.

"I thought you simply looked… but… you are truly that young? I suppose as a foreigner I have no place to judge your lifestyle, so I will simply express my surprise that you are so young. And you are in fact the perfect age for our school. Generally ages range from our first years at about eleven to our seventh years at seventeen or eighteen. I suppose I could pass you both off as fifth years, to keep you close to Mr. Potter, who is currently in his fifth year."

"Moving on," Tsunade said, waving her hand, "Again, you will be gone for ten months in a distant country. Neither of you are exactly in charge of this mission, you are equals in this. You are to send progress reports at the end of each month. Dumbledore-san will help you with how to do so. Now then you are to pack your regular mission supplies and some civilian clothes, if you have none" – a pointed look at Sai – "Purchase some. You have a very loose budget for the mission; Dumbledore-san is paying for everything you require. The rest of what you need will be bought once you arrive at your initial destination; these are things that will be required for you fit your covers. Any questions?"

She was met with silence and then nodded to the pair.

"Good, then you are dismissed, you are to meet back here tonight at eight sharp," Tsunade said, straightening her back, stretching her arms above her head with a yawn. Shizune took the opportunity and snatched the bottle of sake from her hand and ran, Ton-Ton squealing in her arms.

Tsunade's expression darkened and she looked at her now empty hand for a moment before snapping at Sai and Sakura.

"What are you two still doing here? Scram!"

Unwilling to risk her wrath, in an instant Sakura and Sai were walking down the path just outside of the Hokage Tower. Sakura's brow furrowed in thought.

"This is going to be an… interesting mission," She said looking over at Sai.

He favored her with a smile and then slight nervousness crept into his expression.

"Hey, hag, where could I buy some civilian clothes?" He asked.

Sakura laughed lightly and took hold of his wrist beginning to pull him along behind her.

"Come on, let's go find Ino."

Reviews are love!