First Hokage's Necklace

Owners
 * Hashirama Senju - Deceased
 * Tsunade - Former
 * Nawaki - Deceased
 * Dan - Deceased
 * Naruto Uzumaki - Current - Destroyed

History
This was a necklace that was owned by Naruto Uzumaki. It was made from a rare expensive ore and was first owned by the First Hokage, Hashirama Senju of Konoha. He later passed it on to his granddaughter, Tsunade. On the twelfth birthday of her younger brother, Nawaki, she passed it on to him as a gift. Nawaki promised that he would protect Konoha with the necklace. However, during the Second Great Shinobi War, Nawaki was killed and Tsunade would later give it to her lover, Dan. But during the war, he was killed as well, and Tsunade went back to owning it. At the beginning of the Tsunade Retrieval arc, Tsunade made a bet with Naruto that if he could master the Rasengan by the end of the week, Tsunade would give him the necklace, would believe that Naruto will become Hokage someday, and would come back to the village and heal Sasuke and Kakashi. Like most of her other bets, Tsunade lost and Naruto got the necklace. When Naruto drove himself to fight with Tsunade, she saw he could fulfill his dream to become Hokage one day. For that reason she felt the necklace had found someone deserving so she gave it to him as a present. This necklace was regarded as having a curse on it and only Tsunade could wear it; since both Nawaki and Dan died after receiving it. During Jiraiya, Naruto, Tsunade, and Shizune's battle with Orochimaru and Kabuto; Naruto was injured and was almost killed. It can be assumed that Tsunade wanted to break the pattern of death surronding the necklace. Naruto seems to be an exception to this since he has worn it for most of Part I and Part II and has not died yet. Or, the "curse" might just be a coincidence. Most recently, Naruto, in his six-tailed transformation, destroyed the necklace after it attempted to seal the Kyuubi's chakra during his battle with Pain.

Abilities
A power unique to the First Hokage was the ability to control Jinchūriki and the Tailed Beasts. This ability was enhanced by the necklace, it responded to his chakra, which in turn allowed him to control the chakra of the Jinchuriki. It is said that the First Hokage's Hokage-style Sixty-year-old Technique - Kakuan Entering Society with Bliss-bringing Hands responds to this necklace to suppress the Kyūbi's Chakra and saved Naruto after entering Four-Tailed Transformation.