The moment Kakashi and Yamato attacked, why did Hiruko, with Swift Release at such speed, choose to evade purely through movement instead of seizing an opening and attacking while on the move?
It was not that he did not want to. He simply could not.
Swift Release enhanced movement speed, not attack speed. The instant he attacked, his speed would drop.
The moment he attacked was also the moment others could counterattack.
There were four Konoha ninja present. As Kakashi and Yamato attacked, Hiruko's gaze fell on Sakura and Sai. Sakura was manageable—her reaction was a beat slow, but she remained on guard and protected the two men's flank. Sai's reaction was rather interesting. He used offense as defense, like an assassin lying in wait, counterattacking the instant Hiruko attacked. It was thoroughly Root in style.
The second weakness of Swift Release was its consumption. Maintaining high-speed movement not only burdened the body, but also consumed an enormous amount of chakra.
Hiruko had plenty of chakra, but not enough to squander at will.
So, he merely used Swift Release to dodge their attacks, widen the distance, and buy himself some time for trash talk.
Ninja Art: Super Beast Imitating Drawing!
Taking advantage of the gap while someone else was talking, Sai drew a swarm of rats.
The ink rats scurried about the ground without any pattern, occasionally leaping up to attack. They could not inflict any substantial damage; they were simply irritating.
It was just that Hiruko...
"Seems you aren't the type to surrender obediently. Fine... As long as you stay alive, that's enough. I'll just beat you half to death."
Facing four alone, Hiruko remained utterly calm. "Kakashi, if I hadn't encountered Akatsuki and found those legendary eyes, I would have come for that Sharingan of yours long ago.