Shikotsumyaku: Turtle Shell Defense

The user of this Shikotsumyaku jutsu manipulates their ribs and the bones of their back. They create a shell on their back, which is large enough for them to take shelter in, like a turtle. It is a powerful defense, the bones solidifying into being harder than steel. The shell's strength does depend however, on the user's chakra control. But the only downfall to this technique is that they must remain steady while using it, unless used with another technique.