Mahoutsukai ni Narenakatta Onnanoko no Hanashi

Both are set in a magic school where the protagonist struggles with magic. 

MC is girl who want to be magician, but is bad at magic. Both have mentor who motivate them to become witches. it's interesting to watch, if you like animations and films about magic.  

Both anime about a girl who encountered hardships through her life, but is striving. Both fluffy healing anime. 

Similar in: -artstyle -mostly girls setting -magic - fluffly aesthetic anime 

Both Mahonare and Assassination Classroom explore the underdog phenomenon, where characters relegated to a lower status due to perceived inferiority challenge their elite counterparts through sheer determination and growth. In Mahonare, the protagonist, deemed unfit for elite magical training, defies societal expectations by relying on her unwavering resolve and magical affinity to pursue her dreams. Similarly, in Ansatsu Kyoushitsu, the students of Class 3-E, marginalized as failures within their school's rigid hierarchy, find purpose and motivation under Koro-sensei’s unique mentorship, enabling them to surpass their rivals in unexpected ways. Both narratives highlight the transformative power of creativity, innate talents and self-belief, emphasizing that success is not bound by societal labels. read more 

Both animes are about main character who has no power and ends up in a classroom full of the low rank peoples. Even though they're looked down upon from all the other classes in the school, they strive to become successful and not give up.