Aguri acts as the moral compass of the episode. As his captive watcher, she is the first person to look at the world’s most dangerous man and see a student rather than a monster. Her influence is a testament to the series' core theme: the power of a supportive educator. She doesn't fear his power; she pities his lack of purpose. Her death is the episode's tragic climax, serving as the "assassination" of his old identity and the birth of his new mission. From Assassin to Educator
The episode chronicles Koro-sensei’s origin as the "God of Death," the world’s most efficient assassin. This backstory recontextualizes his character; his immense power was never a gift, but a product of a life devoid of human connection. Before becoming a teacher, he viewed people only as targets or tools. The narrative suggests that his ultimate transformation wasn't triggered by the laboratory experiments that mutated his body, but by his interaction with Aguri Yukimura. Aguri Yukimura: The Catalyst for Change Ansatsu Kyoushitsu (TV) 2nd Season Episode 16
The most poignant revelation is that Koro-sensei’s pedagogical genius is born from his greatest regret. He failed to "see" Aguri's heart until it was too late, just as he had spent his life ignoring the humanity of others. His vow to teach Class 3-E is an act of penance. He uses the same observation skills he once used to kill to instead identify the unique potential and insecurities of his students. Conclusion Aguri acts as the moral compass of the episode