Chapter 171

The transformed Reaper fixes a hateful stare on Korosensei, prompting Yoshida to remark that the creature's body is now as hideous as its face. Yanagisawa explains that he subjected the Reaper to the very alterations once forced on Korosensei, the sole distinction being that this recipient welcomed them. The monster then whips its arms out, hurling both Korosensei and the class to the earth.

Between strikes, Yanagisawa boasts of the tentacles' figures: an opening velocity of Mach 20 climbing to a peak of Mach 40. He notes the Reaper mastered them instantly, yet unlike Korosensei's, these limbs were never built to last, cutting the host's remaining life to three months. That disposability, he gloats, spares him any upkeep and removes the risk of a detonation, making the Reaper his flawless weapon.

Kayano taunts Yanagisawa as a coward hiding at a safe remove. In answer, he injects a tailored strain of the cells that leaves him human while lending him strength, then vows to destroy Korosensei even if it costs his own life. Held fast by the beam of Yanagisawa's artificial eye yet still parrying the Reaper's blow, Korosensei tells the class that even a combat-averse assassin eventually meets a moment demanding every skill he owns, and that moment has now come for him.

The chapter is called Rasubosu no Jikan in Japanese and is set between Next Generation Time and Students' Time.