Challenges
Harry Potter/Naruto:
Albus Dumbledore, in a need of a champion, whisk away a little boy from his dimension. This little boy is then known as Harry Potter, the boy-who-lived. At age 15 Harry finds out the truth and tries to find a way back to his home.
Rules:
Harry is the older brother of Hatake Kakashi and was whisked away at the age of 1. Kakashi at that time was barely a few days old.
There was a backlash of magic when Harry was taken. This caused a sort of explosion in the area. Harry's mother was killed because of this.
Harry finds out the truth at age 15 and doesn't want anything to do with the wizarding world anymore.
Harry can't find his way back until Kakashi is send to the outside world for a mission.
The Sanbi was sealed inside of Harry by the wizards.
The only things the wizards are better in than the shinobi are sealing (using runes) and making potions.
The rest is up to you guys.
Things I also thought up:
Kakashi getting badly hurt or poisoned by the wizards. Harry finds him and trying to heal him. Eventually they have to leave because Harry is being chased by the wizards.
Kakashi had gotten hurt because he lost control of his emotions as he found out the wizards had taken his son away from him the same way Harry had been taken.
Sirius is still partially alive, though he can't return to his human form, since it was the human side of him that only died.