|Twenty-Third Period: Final Boss Time|
|Romaji||Rasubosu no jikan|
|Manga Chapters||Chapter 172|
|Previous Episode||Happy Birthday Time|
|Next Episode||Graduation Time|
|Japanese||June 16, 2016|
|Opening||Bye Bye YESTERDAY|
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 Korosensei human was already outside the house.
- When Yanagisawa instructs God of Death to attack the students, he instruct him to attack multiple times in the anime instead of three times in the manga.
- 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.