1x12 - Hand Shakers

Tazuna and Koyori are facing off against Koyori's sister and the doc's old partner. Koyori's sister has been reduced to an emotionless mute after years of difficult treatments and abuse. Can the two of them bear to hurt someone so close to Koyori? And even if so, can they win against Handshakers who are so much more powerful and determined?