Yûsei Matsui

When an octopus-like alien destroys part of the moon, Nagisa Shiota and the rest of the students of E Class of Kunugigaoka Junior High School are given the task to kill him by the government after he decides to act as teacher for their class otherwise he will destroy the Earth once the school year is over. (imdb)

The story of the assassination classroom and their teacher target continues with the students' own conflicts, Korosensei's identity, and the fate of the world as the deadline for assassination approaches.

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