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 in a flashback on wanting to become his apprentice, it happens right after he kills his father but in the manga it happens when human Korosensei was already outside the house.
 * In the anime it doesn't reveal every and each of Korosensei's expressions while in the manga it reveals every expression that Korosensei has.
 * When Korosensei asks Nakamura to get the cakes, the damage in the anime was less than in the manga itself as the cake was not entirely ruined by the soil. This includes during surgery when Korosensei eats with a fork in the anime, while in the manga Nakamura feeds him.