Jewel of the Dragon's Neck

The is a strange metal sphere with an exposed, yellow, glowing core. The jewel was found by Kanna in the basin of a shallow stream, surrounded by large bones, possibly belonging to a dragon. It signifies the element metal and is represented on Kaguya's seal by the color yellow. It was cast into Lake Yamanaka with the verse: "Oh arrow of mine with power pure and immense to slay the dragon, do your good deed fast and swift; grasp the crystal in its neck."