Talk:Owl (Quinque)/@comment-27283194-20160424183323/@comment-10733658-20160426115242

I agree with Orfika, it was probably a Kakuhou inside his shoulder and Arima cut it out when took Yoshimura's arm.

If you notice, the flashback where Eto recalls being defeated by Kuroiwa shows the "fatal damage" she took was along the collarbone.

So likely, both Yoshimura and Eto have kakuhou in the shoulder itself as well as their back. (Along the shoulder blade.)