Naruto/Avatar the Last Airbender Worlds Collide Book 1: Water

Chapter 6: An old legend

The Hidden Leaf Village is the home of Naruto Uzumaki, and recently the people in the village has been in a panic following the disappearances of Naruto and Sasuke Uchiha. The leader of the village, the 5th Hokage, Tsunade was hard at work reading whatever scrolls she could, trying to find some clue about finding a way to travel between their dimension to the one where Naruto and Sasuke currently resides. She wasn't the only one... two of Naruto's teachers Jiraiya of the Sannin and Kakashi Hatake were also reading through many scrolls trying to find clues as well. Jiraiya then came across one of the journals of the 4th Hokage, Minato Namikaze, and he began to read earnestly. Then Jiraiya gasped.
"Master Jiraiya, what is it?" Kakashi asked.
"Tsunade, I would like to take Kakashi with me on a journey." Jiraiya suddenly spoke urgently. Tsunade glared at Jiraiya.
"ARE YOU SERIOUS? AT A TIME LIKE THIS YOU WANT TO TAKE KAKASHI WITH YOU ON A JOURNEY TO PEAK AT WOMEN IN THE BATHHOUSE IS THAT IT?" Tsunade yelled. Jiraiya nervously chuckled and shook his head.
"No no no. It's not that, I promise. There's something Minato said in his journal. During the last Ninja War, shortly after the death of Obito, Minato was sent to the ancient shrine caves near the border between the Land of Fire and the Land of Wind. In the journal, Minato said that once he visited the main shrine, that he was given a prophecy that may connect to the one that the Elder Toad told me a while back." Jiraiya explained seriously. Kakashi's uncovered eye widened.
"What does it say?" Kakashi inquired.
"The supposed prophecy said that once two worlds were one... but after the arrival of some Divine Tree, the world split into two and became seperate dimensions. The prophecy stated that the two worlds would one day be connected again by the Saviors of Each World... their respective Children of Prophecy. Prehaps if Kakashi and I enter this shrine, we could see if Naruto's disappearance has something to do with this old legend." Jiraiya explained. Tsunade stood there, lost in thought before nodding.
"Jiraiya, Kakashi. You now have official orders to go to the shrine caves near our border with the Land of Wind and uncover what leads you can concerning the disappearance of Naruto and Sasuke. This is classified as an S Rank mission." Tsunade announced. Jiraiya smiled.
'Don't worry, Naruto. We'll bring you home soon.' Jiraiya thought.

Jiraiya and Kakashi leaped from the trees with a speed that only ninja could attain.
"Master Jiraiya, that old legend... the whole our world used to be bigger before it was split in two thing... you never believed in that legend before. I'm honestly confused on why you would consider the possibility of it's validity now." Kakashi told Jiraiya.
"You see, Kakashi... a while ago, I recieved word from one of my toad summons... Gamakichi that Naruto was in another universe... a universe where a shinobi once fell into and created chakra pathways into... only one shinobi was rumoured to travel into another dimension before... Minato. However... the main reason I never believed it is because there was no point in time that could explain Minato disappearing for so long... however... Gamakichi was summoned to that dimension... it was real. I have to know why did time pass in a way that it was like Minato never left this world." Jiraiya explained. Kakashi pondered this. However, unknown to them... a figure was watching them from a distance.
"My, my. This looks like this could be interesting." an elderly voice spoke to himself with a chuckle.

Meanwhile in the Avatar universe:
"Wait... we are we going again?" Naruto asked as he sat atop Appa along with the rest of his friends.
"The Earth Kingdom city of Omashu." Aang replied.
"Oh ok." Naruto replied. Sokka sighed.
"Just don't forget it again... this is the third time Aang answered that question." Sokka said. Naruto groaned. 
"It's not like I'm from this world or anything." Naruto pointed out. Katara then looked at Naruto.
"Anyway, it's time to continue teaching you more about this world Aang. So like I already pointed out, those in the Water Tribe often wear lots of blue, while the Air Nomads wore lots of yellow and orange. Can you guess what color is commonly used in the Earth Kingdom?" Katara asked.
"Brown like rocks?" Naruto asked. Katara giggled.
"Nope. The Earth Kingdom citizens wear lots of green." Katara replied. Naruto now hoped beyond hope that they didn't have extremely bushy brows and know an awful sunset, beach genjutsu thing that no one could explain... he enjoyed hanging out with Rock Lee and Might Guy... but not even he could handle a entire nation of 'Bushy Brows'!