Disclaimer: I don't own Naruto or any of the characters I mention. But I do own a computer and that's why I'm here.
The Closed Box Theory
Inside the Hokage's building there is a room. This room contains boxes. One box for every ninja in the village, a place for them to store their most loved possessions safe from harm. Only the ninja in question has the ability to open their box and unless they leave instructions for what the village is to do with the box after their death, it is destroyed without ever being opened. The exception to this rule is missing nins, where the Hokage forces the box open to inspect the contents.
The box was twenty centimetres length and breadth and ten in depth. The only difference was the Hokage's, which is an entire room. The Yondaime's room has been sealed and his last will and testament states that it should be left to the next Namikaze to become Hokage.
This is a tour through the stories behind some of the items in some characters boxes.
What's in Sasuke's box?
When Sasuke's box was first forced open its myriad of contents confused the Godaime, upon further investigation she was able to identify all the objects.
The first she removed was a pressed flower, she thought at first it was probably from one of his many fan girls. However after asking questioning the boys one time devotees she found that none of them recognized it, not even the Yamanaka. After study at the library she found the answer.
Sasuke received the flower from his mother on his sixth birthday. This was a minor tradition of the Uchiha woman, when their children reached eight they were considered old enough to be a threat to them, if they threatened the family or were taken hostage she could kill them. The point of the flower was that it was the symbol of their love for the child. The child was not told of the fact until the night of their sixteenth birthday by which point all Uchiha ninja were expected to have achieved Chuunin (or started their own business for the ones who weren't). Sasuke had never been told this and had merely kept it as a beautiful gift from his mother, not seeing through the fake version of love she gave him after that day.
The next item out of the box was a blood coated senbon. Sakura recognized it as one of the ones that Haku had used to attack team seven. Tests of the blood confirmed it to be Sasukes. He had never told anyone about the retrieved weapon. Sasuke had kept it to remind himself that for now there will be people who are stronger, faster and smarter.
A marble that glowed when chakra was passed through it. A training tool from Sasuke's farther.
Identical jutsu scrolls from Sakura and Ino, given on the gennin graduation day. There was also a hair bow from sakura and a family jutsu scroll from ino. There were other small objects from the pair of them. Sasuke had never forgotten the fan girls who loved him and had a very small place in his heart.
The last was a picture of Sasuke's family together. His shrewd farther, false loving mother and cold stoic brother, sasuke stood before his mother with a shy smile on his face. Itachi next to their farther, both sporting identical Jonin gear and blank looks. As the Hokage looked at the photograph she saw slash marks around Itachi's face, as if someone had tried to remove him but couldn't. Sasuke, after everything that his brother had done, still could not give up totally on him and so put the photograph in the box so that one day he could come back. That would be the day he killed his brother, he would cut out his own heart if it meant he could cut out that face without the pain.
Some of the objects were placed in a special display as one of the most famous Konoha ninja. His card reads: Objects belonging to the traitorous last Uchia. Look at these objects and try to find what turns a man mad.
It is visited regularly by Sakura and Ino, both of whom leave a flower on his leaving day, and then try to get on with there lives.
What's in Neji's box?
Neji has only two things in his box. The first is a Photograph of him and his farther, taken shortly before he was given his caged bird seal. The photo is warn from rubbing at two points, on Neji's own forehead where he remembers life before control was branded on him. The other was his father's lightly smiling face, where he remembers happiness before the branding.
The other object is a seal array on a piece of leathery dried skin. Nejis first attempt to find an alternative to the caged bird seal. It was the culmination of three years hard work, trial and effort had been put in by Neji, Tenten and Lee. They decided to try it three months before naruto returned; neji was to be the test subject with lee drawing as they wanted no chakra in the seal when they started, lastly tenten was to start the seal reaction so that it could only be broken by her. The seal was placed on the back of his head and his heir was shaven and the seal written.
It went drastically wrong. When Tenten chakra flowed through the seal it attacked his chakra system damaging the circulation slightly, he would have only had to spend the week in bed if it hadn't been for Lee. Scared by what was happening to his team mate he grabbed one of tenten's swords and scalped him to remove the seal. Plastic surgery saved his scalp and some dubious kunoichi Jutsu he soon had his hear back. They told their Sensei as well as the rest of the Hyuuga clan that tenten had just been a little overzealous with her training.
He keeps the seal and keeps trying to find his alternative, but he keeps the seal as a reminder of another piece of brilliant team work.