"Goodbye, Mr. Despair"
A manga series by Kumeta Kouji that ran from 2005 to 2012. Was adapted into three one-cour seasons of anime by Studio Shaft.
The series is essentially an episodic satire on Japanese and foreign culture, among others, as seen from the point of view of manic-depressive, suicidal homeroom teacher Itoshiki Nozomu and his psychologically dysfunctional class.