Secret Shikotsumyaku: Dark Demon

An ultimate Shikotsumyaku technique, used by a clan Head in the Warring States Period. By utilizing the Transformation Technique with Shikotsumyaku, Senmaro was able to morph his entire body into a construct of black bones, a demon of sorts. This form is an advanced application of Transformation. In this enhanced state, the users physical abilities and speed are boosted, along with their five senses. They become more bestial, reminding a few of a Tailed Beast Form. The user's speed is also increased in power, along with Nature Transformations, Shikotsumyaku, and other ninjutsu. More advanced Shikotsumyaku is possible in this form. Also, this form is very durable, not being crushed by powerful Earth Techniques, and can regenerate, if it's managed to be destroyed somewhat.

This technique cannot last forever though, as it does consume chakra. Though masters of this ultimate Shikotsumyaku technique can keep it going for extended periods of time.