Shadow Sword Jutsu

Katsuo gathers chakra in his Bone Katana, gathering it directly in any particular point of the blade. Once done, the user then uses the ability of the Shikotsumyaku to create new bone from the blade's edge. This creates a spike jutting from the blade, its exact angle and length depending upon where and how much chakra was put into it. This sprouting bone has the strength and speed behind it to pierce both flesh and bone, making it a fatal jutsu for those skewered by the sprouting bone. After its used, the bone can be harmlessly detached from the blade with damaging the blade itself or its edge.