^I haven't finished the manga of Zetsubou Sensei
Tell me the ending
Spoiler for ending:
Kafuka Fuura turns out to be dead all along and possessing the girls who received her organs afterwards. He marries and divorces girls daily based on her possession.
At the end of the manga there is a time skip where it is shown that Kyosuke never got the chance to confess to Aiko before she went to study abroad and married Shunka instead. I thought it was a dream until the last page.