In class 3-3 of Yomiyama North Junior High, transfer student Kouichi Sakakibara makes his return after taking a sick leave for the first month of school. Among his new classmates, he is inexplicably drawn toward Mei Misaki—a reserved girl with an eyepatch whom he met in the hospital during his absence. But none of his classmates acknowledge her existence; they warn him not to acquaint himself with things that do not exist. Against their words of caution, Kouichi befriends Mei—soon learning of the sinister truth behind his friends' apprehension. The ominous rumors revolve around a former student of the class 3-3. However, no one will share the full details of the grim event with Kouichi. Engrossed in the curse that plagues his class, Kouichi sets out to discover its connection to his new friend. As a series of tragedies arise around them, it is now up to Kouichi, Mei, and their classmates to unravel the eerie mystery—but doing so will come at a hefty price.

Special episode included in the Blu-ray Box of Ano Natsu de Matteru.

In the Binfield Kingdom Chronicle, it is said that there was once a small, peaceful country called the Kingdom of Winfield, whose king and royal family possessed great white wings. Hamura Shou is newly enrolled at Yuusei Academy. After hearing about a student named Misonou Kai from the headmaster, Shou comes to believe that Kai is his younger twin brother, who he was separated from when he was younger. However, after a mysterious earthquake, Shou is suddenly carried into another world with two other students. It is in this new world that, after being attacked by a monster, Shou suddenly unleashes great, white wings.

Returning from their summer vacation, the students of Class 3-E at the prestigious Kunugigaoka Middle School find themselves up against unbeatable odds. Faced with the possibility of world annihilation, the students must come up with increasingly elaborate and creative ways to kill their teacher, the cunning yet optimistic and helpful Koro-sensei. However, eliminating Koro-sensei is not the only objective the students need to worry about. Gakuhou Asano, the academy's merciless and cruel principal, seeks to prevent Class 3-E's success by brainwashing his other hard-working pupils into ruthlessly competitive studying machines. Hostility begins to linger in the air as traitors and killers alike attempt to claim the bounty on Koro-sensei's head for themselves. Nagisa Shiota, one of Class 3-E's most skilled assassins, finds himself in the middle of the conflict. While he works to maintain his academic standing and prevent the end of the world, domestic affairs jeopardize his place in Class 3-E. Together with his dedicated classmates, he must now face the threats head-on.