"I'm not going to kill you," Ittoki said, his voice steady for the first time. "Because if I do, someone else will come for me. And then someone will come for them. I’m done being a spoke in your wheel."
As if on cue, a flurry of shuriken whistled through the air. Ittoki reacted by instinct, his Iga-built suit whirring to life, enhancing his speed just enough to deflect the steel. Out of the darkness stepped Haruka, a Koga student whose eyes held a fanatical gleam. Shinobi no Ittoki (Dub) Episode 5
The battle that followed was a blur of high-tech gadgetry and ancient martial arts. Haruka was faster, his movements honed by years of brutal Koga conditioning. But Ittoki had something the Koga lacked: a reason to live beyond the kill. He didn't want to conquer; he wanted to protect the small, quiet life he had left behind. "I'm not going to kill you," Ittoki said,
Kousetsu finally turned, her mask reflecting the dim light of the artificial moon. "It’s a cycle, Ittoki. A wheel that keeps turning. We are just the spokes." I’m done being a spoke in your wheel
Here is a story expanding on the themes of that episode, focusing on the weight of heritage and the "cycle" that traps these young ninjas. The Weight of the Blade