Sekkyoku is the sword which Odayaka uses in rare circumstances. He almost never uses it as a sword, instead using it as part of his jutsu. He created it from the Kokutris which he had killed as a baby. He took its bones and scales, and mixed them with steel to crate the blade, and its feathers decorated the hilt. He put its eye in a gem, using the Forever Fossil seal of the Land of Beasts, and put it in the hilt. He named it Sekkyoku, meaning Aggressive, as a testament to the nature of its original form.The creation retains some of the powers of the original creature, such as its deathly bite, and the ability to release poison from its feathers. Using the Gyaku Kokutris Kinjutsu, Odayaka can, using the blade, activate its powers to the point where he is essentially summoning the Kokutris. It can also extend the blade by separating into segments, connected by bone. He can also extract the highly pressurized bone of the beast for use in his Black Bone Ward.
Sekkyoku was destroyed during Odayaka's fight with Sasori.