Assassination Classroom › Season 1

Chapter 4 — Grown-Up Time

Class 3-E gets a new foreign language teacher, Irina Jelavic, who is actually a professional assassin with no interest in teaching the students. Irina attempts to seduce Koro-sensei so her team of assassins can kill him, but this fails as a result of using the wrong ammo and failing to notice his keen sense of smell. Later, after the rest of the class rebel against Irina when she refuses to teach them properly, Karasuma shows her how dedicated Koro-sensei is to teaching his students and how important education is for assassinations. Realizing the error of her ways, Irina begins to earnestly teach her students, who give her the less-than-appreciated nickname of "Bitch-sensei." (Source: Wikipedia)