Soooooo Koro-sensei Quest. Also called Koro-Q, this is the entire plot of Assassination Classroom, shorted down to twelve, ten minute long episodes set in a fantasy RPG world, with a chibi art style on top of everything. Sound goofy? You’re damn right.
The show is not meant to be taken seriously, and is constantly making fun of itself. The story kinda follows the same plot as the original series, with changes being made to fit the new setting, or for jokes. The characters all lose some dimension to their characters, many of which just becoming single joke characters, but that’s due to the style of show and essentially half a season worth of time they had to make the show.
Koro-Q’s artstyle and colors are very bright and cheerful. Some aspects of the show don’t really make sense, but don’t really need to since it’s not taking itself seriously. I strongly recommend watching Assassination Classroom in its entirety before watching Koro-Q.