Confession Time

Kayano's assault intensifies as the tentacles devour her mind, and Korosensei warns that saving her means removing them mid fight, with no time to calm her rage as they once did for Itona. He will bait her by exposing his weak point so the students can subdue her for an instant. When he catches and restrains her, Nagisa steps up and, refusing to believe her whole year was pretense, kisses her, jolting her back to awareness before she blacks out. Korosensei then extracts the tentacles from her neck.

As classmates crowd around and Irina critiques Nagisa's technique, a hooded sniper fires an anti sensei round. The gunman's companion is Shiro, who peels off his mask and voice changer to reveal himself as Yanagisawa, vowing to finish Korosensei by March before the pair withdraw. A recovered Kayano admits her resolve had wavered over the year, only for her tentacles to override her doubts, and Nagisa comforts her as she weeps in relief at finally dropping the act.

Isogai again demands the truth, and Korosensei confirms that until two years earlier he was the Reaper, and that he will die in March by an assassin's hand or by exploding. He narrates his origin: a boy from a war torn land who knew only death and became an assassin, earning the Reaper name over a decade of killings before capture turned him into Yanagisawa's test subject.

In the lab he grows close to Aguri Yukimura, a worker he first hopes to exploit for escape. She refuses to free him, yet as they talk he begins to change, learning she teaches at a school and grasping her lesson that the apprentice who betrayed him had simply longed to be truly seen. By the time she asks him to review the exam questions she has prepared, the two have quietly become close, mere weeks before the permanent crescent moon forms.

This installment debuts the fourth opening theme, Bye Bye YESTERDAY, and the title card shifts the series branding from Second Season to Final Season. Unusually, Korosensei narrates the second half in place of Nagisa. The anime trims several human era escape attempts shown in the manga and omits Shiro's stated profile as well as an ended civil war among Korosensei's listed feats.