Mai Fuchigami

The OVA that tells the story of the battle between the panzers of Anzio Girl's Highschool and Oarai High School.

A powerful creature claims that within a year, Earth will destroyed by him, but he offers mankind a chance by become a homeroom teacher where he teaches his students about how to kill him. An assassination classroom begins. (imdb)

Ooari girls academy faces closer once again and the Tankery club girls must participate in another match to save their school from permanent closure! (imdb)

Get ready for a strange but fun-filled adventure with your favorite group of assassins. The killer class is back but this time they've got…magic. In this brand new spin-off series, follow the chibis of Class 3-E as they learn swordsmanship and sorcery at Kunugigaoka Magic School. Their mission... Defeat the evil Demon King Koro Sensei and face the trials and perils of their magical school. (ANN)

Assassination classroom : 365 days time period is about Nagisa and Karma coming back to their classroom 7 years later. (imdb)

After global warming causes sea levels to rise, a mysterious group of warships appear all over the world and defeat humanity. 17 years after the devastating naval war, a group of people combat the warships with a mysterious submarine. (imdb)

As the Blue Steel gets closer to understanding the origins of the authority controlling the enemy, Iona's past starts to reveal why the war began and her reason for siding with humanity. (myanimelist.net)