The Kusanagi Sword is the Kusanagi of Japanese legend. Orochimaru retrieves his Kusanagi by opening his mouth and extending a snake which then opens its mouth and produces the sword. Orochimaru was seen producing the sword handle first so he could use it freely, or blade first to attack his opponent instantly. The sword can extend its blade to attack from afar and it can cut through almost anything. Itachi Uchiha took the original from Orochimaru once he killed him. After Itachi's death at the ands of Seiame Tsumaru, the blade has passed hands yet again.
Sasuke Uchiha refers to the chokuto he carries as a "Sword of Kusanagi", but it carries none of the unique attributes that Orochimaru's does.
Yamagakure 2 Version
Yamagakure craftsmen were able to replicate, Sasuke's Kusanagi and make standard copies of it. During the Chunin Exams, Yamagakure Genin are given a sword in which they can customize later. It can cut through anything, cannot be broken and has the ability to extend and absorb chakra nature.
Seireitou Hyuga's Version
Orochimaru gave Seireitou his own personalized version called the Hakunagi