Aside from its rock-hard bones, another reason engineering drills struggled to pierce the skin of Yamata no Orochi was its terrifyingly potent regenerative ability.
The "Holy Remains" resided within this massive body, and the Bloodline inherited from the White Emperor granted it extreme resilience. Even wounds deep enough to expose bone healed at a visible rate. If a drill bit stopped rotating inside its body, it would slowly be "squeezed" right back out by the surging, rampant flesh.
With no other choice, the researchers had to continuously spray liquid nitrogen onto the spots the Shieki Eight Families had drilled through, using sub-zero temperatures to suppress the creature's cellular activity and slow its recovery.
Chapter 612