Episode 45

Final Boss Time is the twenty-third episode of Season 2 and the forty-fourth episode of the Assassination Classroom anime. It premiered in Japan on June 16, 2016.

Summary
Korosensei faces his former apprentice and Yanagisawa in a life-or-death battle. When Yanagisawa switches his focus on the students, Kayano sacrifices herself to buy Korosensei time to recover, leading to one final clash.

Anime and Manga differences

 * When God of death meets Korosensei on flashback on wanting to become his apprentice, it happens right after he kill his father but on manga it happens when Korosensei human was already outside the house.
 * When Yanagisawa instruct God of Death to attack the student, he instruct the attack multiple times on anime instead of three times on manga.
 * On the anime it doesn't reveal every and each of Korosensei's expression while on manga it reveals every expression that Korosensei has.
 * When Korosensei asks Nakamura to get the cakes, the damage on anime was lesser than on manga itself as the cake was not entirely dirted by soils. This include during surgery, Korosensei eats with fork on anime while on manga Nakamura feeds him.