As he fought "Yoriichi," Xia Xi gradually noticed a few details.
This puppet.
It was different from living Swordsmen who used Breathing Styles.
Its energy level never fluctuated, yet it could deliver combat power slightly above what that energy level should allow.
Primarily, it used its six hands to compensate for its insufficient strength.
One blade couldn't deliver a strike on the level of the Nine Hashira?
Then use two blades at once!
If two weren't enough, then three!
Through rapid strikes and precise coordination between six blades, it barely managed to push its damage output to the Nine Hashira's passing mark.
Those Hashira of the past, whose energy levels had been somewhere over two hundred.
Those "gatekeepers" who had mainly relied on Breathing Style multipliers to contend with Lower Rank Demons had probably been about this strong.
But from another perspective.
"Yoriichi" was actually stronger than those nameless members of the Nine Hashira in some respects.
After all, it didn't fear pain.
It never hesitated in battle.
Nor would it suffer debuffs from poison, curses, and the like.
And...
"How on earth does winding this thing's spring a few times give it this much power output?!"
Even someone as knowledgeable as Xia Xi found it incredible.
It didn't have an engine or a power reactor inside.
It moved entirely on the seven or eight turns Tetsujin had given its spring.
Xia Xi raised Sandai Yasushi and casually parried a few blows.
He deliberately felt the force transmitted through its slashes.
Although it fell well short of Igarashi and the others.
It was definitely at the Provisional Hashira level.
How did this gear-and-spring supertechnology let a pile of wood and metal slash with dozens of tons of force?
What about conservation of kinetic energy?
What about materials science and dynamics?