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?
That's why he gave up doing research.
لهذا توقّف عن متابعة البحث
Darum hat er den Weg der Forschung
hinter sich gelassen.
Por eso abandonó la investigación.
Por eso abandonó la investigación.
C’est ce qui l’a conduit
à abandonner la recherche.
Per cui il professore
Foi por isso que ele 
desistiu de fazer pesquisa.