Vol 4: Chapter 3-1.

The knife’s sharpness was unparalleled. It sliced the wall all the way as they fell. When they got to the sixth floor, the knife finally stopped its vibration. But the inertia still kept them going down. Zheng’s arm absorbed the force that was generated by the sudden drop in speed.

Even his mutated arm was almost not enough to sustain this force. He felt pain from his arm along with the sound of muscle and bones pulling apart....