To begin with, the anime have no story. Evey episode have his own story.
Itoshiki is a teacher in highschool. He is the class teacher of a class full of girls (there are some boys though..) and every girl have her own wierd habits.
Itoshiki is getting despair from things that usually make one lough. he is teaching his students that life not promising and only lead to despair. On the contrary, Kafuka Fuura, one of his students, who always sees everything in the most optemistic way, showing him that life not so bad.
in every episode Itoshiki getting depressed and so on.
I LOVE this anime and especially it's music.
