Episode 44

Happy Birthday Time is the twenty-second episode of Season 2 and the forty-third episode of the Assassination Classroom anime. It premiered in Japan on June 9, 2016.

Summary
After taking out the army unit stationed inside the mountain, Class 3-E reunite with Korosensei. Their celebrations, including a happy birthday to mark another anniversary of Korosensei and Ms Yukimura meeting for the first time, are brutally cut short by the arrival of Yanagisawa and the second God of Death, now a tentacled monster. The pair then battle Korosensei with the students unable to help.

Plot
The episode start with Class 3-E's infiltration to the mountain where the SDF are in panic due not to see them in the dark and they cannot determine their numbers.

Anime and Manga differences

 * The anime replaces Craig Houjou and his Wolfpack group with an elite SDF (Self-Defense Force) commander and his battalion of soldiers.
 * The light on Lance of the Heavens in the anime was less bright for the width compared to the manga.
 * The Command Post is more smaller than what it seems in the anime where it includes the officers in charge as well, where in the anime it involves less people than what it seems. This is also happens when Karasuma wants to go to the mountain with Irina instead of being protested by an officer first before he decides to go.
 * Class E's Super Gym Clothes camouflage are matches with the mountain environment and darkness while in the manga their Super Gym Clothes camouflage was entirely black to match with the darkness.
 * Because Wolfpack did not appear, Karasuma never gave any intel in the anime unlike in the manga where he gives false information to the Wolfpack, the following changes are:
 * When Megu uses her trap, the soldiers are strangled by the neck and finished by Hinata and Kimura while in the anime she makes the soldiers go upside down with her trap.
 * When Karma set up the living bait with his spicy ingredients (Wasabi, chilli, etc.), he did not take off all the gear that soldiers wear(Kevlar, Military Uniform, etc.) while in the manga he only leaves a Wolfpack member wearing only boxer shorts.
 * When a squad was trapped inside a net, only Okajima and Yada struck them with stun guns in the anime instead of Muramatsu, Okajima, Hinano and Yada.
 * When Karma instructs Terasaka's squad to attack, Okuda is with them while in the anime she did not appear and her loadout is a glue launcher instead of a custom slingshot with custom bullets.
 * The match between Class 3-E and the Main Unit Leader (in the Manga it was Houjou while in the Anime it was an Elite SDF Commander), there are some changes in the battle itself.
 * Houjou uses a surprise attack and knocks down one of the class members before the battle starts while in the anime an Elite Commander is standing in their way.
 * Chiba and Hayami snipe Houjou from behind while in the anime they snipe the Commander from front.
 * Class 3-E did not use Hit and Run strategy. Instead they kept attacking head on.
 * Kanzaki did not bring her flashlight. Instead she brings a stun gun in the anime while in the manga she uses her flashlight to blind Houjou temporarily while Sugino throws rocks at him.
 * Houjou was weakened by a tranquilizer dart that hit his neck and sense killing intention before Nagisa ambushes him with a Clap Stun attack while in the anime the Commander was distracted with an Anti-Sensei knife before Nagisa ambushes him with a Clap Stun Attack without sensing any killing intention.

Trivia

 * Since Wolfpack did not appear, some scenes are changed while keeping the thrill in this episode.
 * An Elite SDF Commander was modelled after Kazutaka Shindo, Kunugigaoka's Baseball Captain.