Irina Jelavic

Irina Jelavic is a Serbian professional hitwoman hired, alongside Koro-sensei himself as an unwitting colleague, to help eliminate him, posing as a foreign language teacher at Class 3-E to get close to the students. She was trained by an experienced assassin named Lovro, who shaped her confident, seductive approach to the job long before she ever arrived at the school.

Early on, Irina treats her teaching role as a joke and relies heavily on her looks and charm to get what she wants, which quickly backfires and leaves her humiliated in front of the class. That embarrassment pushes her to actually try harder, and over time her feelings toward both her job and her students become far more genuine. The class, not entirely seriously, nicknames her "Professor Bitch," a label she never quite manages to shake.

Irina's relationship with Tadaomi Karasuma, who oversees the mission alongside her, starts out tense and professional but slowly warms into real affection, and the two eventually marry by the story's end. Despite her rough start, Irina genuinely grows to care about her students' futures, becoming far more than the mercenary she first appeared to be when she walked into the classroom.