The anime series "Sayonara, Zetsubou-Sensei" has 12 episodes , "Zoku Sayonara Zetsubō Sensei" has 13 episodes , "Zan Sayonara Zetsubō Sensei" has 13 episodes . There are two OAVs : "Goku Sayonara Zetsubō Sensei" and "Zan Sayonara Zetsubō Sensei Bangai-chi" .