Isn't this like the modern era version of Death Note?
What? They're absolutely not alike I'm the slightest!
Assassination Classroom is about a mysterious octopus-like being who has destroyed a chunk of the moon and threatens to destroy the earth in a year; since he seems unkillable he proposes to teach the bottom. class of an elite school and also allow them to attempt to kill him during the year.
This is more of an action comedy. Definitely nothing even close to Death Note.
As a fun selling point, the voice of the being (Koro-Sensei) in the English dub is Sonny Strait - who also voices Krillin