The Legendary Magatama.Note: The Narutoverse does not have an "Imperial Regalia of Japan." So this will merely be called one of the three legendary items among with the Kusanagi and Yata Mirror.Appearance: The Yasakani no Magatama is a beautiful necklace with jade magatama stones set into it.
Above: The three legendary treasures, the jade magatama stone is an example of just one stone from the Yasakani no Magatama.
Background Information: Of the three legendary treasures, two of them have been accounted for: the Kusanagi and the Yata mirror. Both of these legendary items offered great capabilities in either attacking or defense and were sought after by powerful ninja. The Kusanagi was said to be the ultimate offensive weapon, its blade is said to be so hard that it is able to slice through anything, even hurting Enma's diamond staff form and its only counter being the equally legendary sword of Totsuka.
The Yata mirror was the ultimate defensive item - able to reputedly deflect all attacks, even Kirin.
The last of the legendary three treasures, is said to be both the weakest and the most beautiful. However, it is rarely sought after due to its rather unique abilities which are worthless to most people and the difficulty in aquiring such an artifact.
The third treasure, The Yasakani no Magatama, otherwise known as the jewel or necklace of jewels was the embodiment of benevolence and the most important magatama of all.
History: The history of the Yasakani no Magatama has always been shrouded in mystery and its passing on from each owner to another has always been blurred. However one thing is for certain, the Magatama, although a legendary item, was never sought after in the same way the Kusanagi or the Yata were. Indeed there are many stories and folktales of people throwing away "Jewels" or a "necklace of jewels."
Whomever created the three legendary items, was from far before the ninja era and before ninja clans even existed. It has been attributed to Rikoudon Sennin, the sage of the 6 paths or to even more enigmatic figures, some people say Gods. The possession of the three items in true recorded history, probably belonged to the first Daimyo of the fire country. From then on, the items were seperated - sought after with bloodshed and scattered across all the other major nations.
The Yakasaki No Magatama, was thus shrouded into Legend and while the Kusanagi was inevitably found by Orochimaru or perhaps even by someone before him and the Yata remained as elusive as ever (Until Itachi found it), of the three legendary items, only the Yakasaki No Magatama was unaccounted for.
Hundreds of years before any of the three items were found however, monks gained the possession of the Magatama, there they used it as a decoration to the statue of Fujin (The Wind God). Ultimately it was stolen by a thief, the Magatama looking merely like a very valuable necklace of jewels was sold on quickly to a rich bidder. From there it passed hands from father to son and so on.
It was at this point in time, that the Magatama was probably thought to have never existed, nevertheless its abilities as recorded in books still interested a few. Orochimaru, always a keen seeker - guessed the location of the family who had the item but thought it was not worth his time when the Yata Mirror offered far greater powers. Over another period of time, Washi stumbled upon the very same book as a missing-nin - realising that his forbidden techniques would be far more valuable with the possession of this item: he decided to look for it.
Unfortunately and to no avail, his two years were not spent well and he gave up what seemed like a hopeless search. By sheer coincidence or perhaps by the mysterious powers of the Yakasaki No Magatama itself, he finally found it when he had at last given up his futile search. A hermit offered him refuge during a mighty storm, Washi accepted and despite being a missing-nin, the hermit was not phased by Washi in the slightest.
They sat in a cave, waiting until the storm would end while the Hermit told stories to Washi. The hermit was once the son of a noble family who was very rich - but through his addiction to gambling and alcohol - he had squandered a huge amount of wealth. Indeed his only heirloom left was a certain necklace with jade magatamas. The hermit gave it to Washi, perhaps realising that in his own old age, he would not survive for long and with no son there would be no-one else to pass on this heirloom to.
Thus, the Magatama passed on to Washi and although, at this point, he had little knowledge of its capabilities - he had begun testing what it could do.
Abilities: The magatama's shape of a sphere with a flowing tail is the usual visual representation of the human spirit (hitodama). Wearing one during life is considered a way of gaining protections from kami (Spirits, Demons, Gods) and yokai (Monsters, Demons, Spirits). While most magatama are worn due to this superstition or due to aesthetics. The Yasakani No Magatama truly has powers of surpressing demonic or spiritual nature and influence. The Yasakani No Magatama can only be removed against the wearer's will (If he is wearing it) by killing the user - as with the other Legendary items: it is indestructible (Or should I say extremely, extremely, extremely hard to destroy.)
Passive Abilities: The wearer of the Magatama has his soul perfectly bound to the body. It can not be sealed away, extracted or removed from the body unless the Magatama is removed first. Any souls or spirits sealed or placed into the Magatama is under an incredibly powerful bind - the Magatama is able to fully supresses demons and souls and they can then be released whenever the user so wishes.
Active Abilities: By using 50 chakra, Washi is able to utilise the full powers of the Magatama, it allows him to see the spiritual world in his right eye - able to see souls and demons and communicate with them. The Magatama also grants a powerful aura that supresses demonic or spiritual power and influence near to Washi.
Notes: Being a Legendary Item, this item takes up a S-rank Jutsu Slot (Or whatever is appropriate, I don't want the item being too OP). If Washi is killed, then the item will pass on to the killer.