Crossover:
Naruto

Timeline:
Beginning any time from Pre-Hogwarts or one of the summers before Fourth Year.

Alterations to Canon:
None.

Pairings:
Harry/Harem.

Story:
Harry comes into possession of a strange blue/green gem-like stone, not unlike the First Hokage's necklace as owned by Tsunade and given to Naruto.

How?
- Garage sale on Privet Drive.
- Found in a gutter, in a garden, in a bird's nest.
- Novelty/Souvenir/Junk store.
Otherwise somewhere that no other magical would have encountered it.

Harry can feel some sort of magical presence from it before he even touches it. Acquiring it he takes it away somewhere secluded and tries to figure out what it is or what it does. Channelling some magic into it as though it were a wand causes the stone to begin glowing until it slowly loses its form and suddenly the blue-green colour is on or rather IN his hand. The coloured shape on his skin begins to unfold into a seal anchoring itself upon him and spreading up his arm and over the rest of his body.

When the seal reaches Harry's forehead it encounters his scar and the soul fragment therein causing a conflict to erupt. Using Harry's magic and driven by the presence within the seal the fragment is expelled even as Harry is rendered unconscious.

He awakens in a mindscape and there he encounters a man who looks to be about fifty or sixty years old, he identifies himself as Naruto Uzukami-Namikaze. The stone Harry found is an experimental educational tool, it contains an imprint, a supply of Naruto's chakra that is shaped into a seal/mold, a pattern which if filled with the chakra of the stone's user, manifests a clone of Naruto with all of Naruto's knowledge.

Since it doesn't manifest a solid chakra construct in reality but only an illusion construct visible only to the user of the stone, it is something more akin to a genjustu than anything else and so the technique isn't very costly, chakra/magically speaking. Naruto explains that his purpose within the seal is to impart any skill that a ninja might need/seek to learn, as sensei who can be consulted at any time.

Naruto is bewildered to learn that one of experimental teaching seal-stones has somehow found its way to what is clearly another world. Perhaps a magical creature from Harry's world which has a summon contract with a shinobi in Naruto's world carried one back, who knows? Regardless Naruto is happy to train Harry in how to use his chakra/magic and begins teaching him how to augment his muscles and bones with chakra for speed and durability, the leaf floating exercise along with illusion, clone and substitution techniques.

Timeframe:
- If Harry is pre-Hogwarts he'll have no preconceptions about what he can and can't do with his chakra, not knowing anything about magic. However it would make Harry so young that he wouldn't have much chakra/magical reserves to use and learn techniques at this stage. He should also learn what he is being taught slowly, not over years like an academy student - the stone is intended to be an improved teaching tool after all - but certainly not really quickly either.

- If during a summer after Hogwarts has started for Harry then it should probably involve some sort of psychological hurdle to Harry trying to channel his magic without his wand and overcoming that. With greater magical reserves Harry should be able to progress through more training more quickly and move onto more advanced techniques and skills, perhaps getting water walking down and learning his first elemental manipulation before the summer is over.

A Ninja at Hogwarts:
At Hogwarts Harry should continue his training as stealthily as he can but with varying degrees of success and while not being afraid to demonstrate some of the skills he has learned when the situation presents itself, especially if he thinks he can get away with using them without anyone connecting them to himself.

As time passes Harry continues to learn more skills, i.e. Shunshin, chakra strings, genjutsu.

Learning to channel spells through his wand at the same time as trying to shape chakra/magic through his body presents a difficult challenge for Harry who, without chakra coils that correspond to those known to ninja in Naruto's world, finds the differing flows sometimes conflict, cancel each other out, amplify each other or that one comes out stronger or weaker than intended. Naruto however treats it as just another chakra control exercise, walking Harry through different drills and patterns as he learns to maintain certain simple spells while maintain chakra techniques like leaf floating or tree walking.

Naruto should also act as a sounding board, an adult voice of reason and consultation that helps Harry make good decisions by helping Harry to reason through things as well as providing him with advice and knowledge not related to ninja training, i.e. diplomacy, budgeting, reading people, strategy, seeing underneath the underneath and, naturally, about girls.

If by this point of the story Naruto hasn't disclosed his backstory now is the time to either make him more akin to what might be expected of canon events from the show/manga, such as having Hinata as his sole wife, or whether Naruto has experienced a more diverse lifestyle with multiple sequential or concurrent partners during his life, for example being a bachelor who has had or maintains several casual relationships or if he has a harem of wives whom he uses his signature technique to keep happy and satisfied.

If the later is true then Harry should follow suit and use his newly acquired skills and knowledge in an attempt, however successful, to gather his own harem. Especially if Harry finds himself capable of creating a shadow clone or two by the time he is in his fourth or fifth year of Hogwarts.

Ideas:
- Channelling wind-natured chakra around himself during flight allows Harry to dominate on the Quidditch pitch, giving him an edge to perform moves and tricks that otherwise would be impossible on a broom.

- Using the Illusion-technique (Henge) provides Harry with the opportunity to impersonate almost anyone at Hogwarts for comedic value, infiltration or even if/when he becomes so inclined, perversion.

- What is the relationship of magic/chakra when comparing kage bunshin clones to conjuring and could the two techniques be combined to create a modified clone, whether kunai or Harry.

- What is the relationship of magic/chakra when comparing apparition with Hiraishin, how do they measure up on range, speed, accuracy and magical anti-teleportation denial, i.e. anti-apparition jinxes.

- Chakra strings launched from his wand can be longer, travel further and are capable of conducting certain kinds of spell effects, for example banishing, summoning, momentum arresting, granting borderline telekinesis with fine enough chakra control.

- Genjutsu's facility for a variety of uses: an anti-legilimency measure, appearing attentive while doing whatever he pleases during class, fooling observers or anyone following him, hypnotism of magical creatures, combined into wards to provide completely different effects.etc.

- Whatever else you can think of adapting, chakra techniques to spells, spells to chakra techniques, utelising either/both for school, training or romance purposes. Trying not to over-power Harry so much that he can surpass any and all obstacles with effortless ease.