Spoiler for latest chapter:
First Ai Kora, now Karin...fortunately, this series had a much better ending than the former.
Two years after Kenta and Karin graduate, the family reveals to Karin that they are going to allow her to live as a human...but to do so, they decide to erase their memories of Karin forever. Anju bids her sister a tearful farewell and says that they can no longer walk together under the sun anymore.
Karin and Kenta are living in an apartment together. Karin is still crying over losing her family, but Kenta wants her to be happy, so after various words of encouragement, he
proposes to Karin 
She tearfully accepts, while several bats watch from outside...
Flash forward ten years. Karin is now living in a large house. She hears a song playing outside, and notices a woman with a black umbrella walk past. It's Anju, all grown up, and it seems she hasn't forgotten about her sister all this time...
Spoiler for discussion:
Karin and Kenta get a happy ending, and Anju is still close to her sister. Maybe the author finally got over her 'misery fetish'
I am curious about Kenta's mom though...does she ever find happiness in the manga? I felt bad for her during the anime since she had the worst streak of luck. Hopefully the author didn't just forget about her...
Ironically, I'm listening to the full anime OP/ED as I write this...JC Staff should make a second season.