Sayonara, Zetsubou-Sensei

A rather long series, the manga Sayonara Zetsubou-Sensei amassed 30 volumes in its run from 2005 to 2012. It received its first 12 episode TV series from July to September in 2007 under the same title. The second season from January to March 2008 had 13 episodes and was titled (Zoku) Sayonara, Zetsubou-Sensei. While it began on the 5th, 2 animations were released immediately before on the 1st ("Zetsubou Girls Collection") and 4th ("Preface/Summary")

The third anime addition was a 3-part OVA series released October 2008 to February 2009 titled Goku: Sayonara, Zetsubou-Sensei. The fourth contribution (and third TV series) was the 13-episode Zan: Sayonara, Zetsubou-Sensei which ran from July to September 2009. Finally a second OVA series (and the fifth anime overall) titled Zan: Sayonara, Zetsubou-Sensei Bangaichi had 3 parts which came out November 2009, February 2010 and January 2012.