I liked this manga until the author decided to end it; the ending was terrible for me. It's been a long time since I read this, but from memory... the MC's brother is part of demon hunting organization, but ultimately, that side plot has absolutely nothing to do with our two MC. That'd be like Sasuke defeating Akatsuki on his own and Naruto just does his own thing. Even if it's a subplot, our MC should be involved somehow...
Next is our male MC, he fails to accomplish anything he said he would. He said he would rescue the little boy and while not verbalized, he did want to be with the female MC. Both objectives are not met although the latter could be part of the future we do not see, but that's stupid. Again, that's like Naruto failing to be hokage and the author leaving Sakura's love ambiguous in the end. (Sorry for the Naruto comparisons, but I think most would understand without me spoiling too much here)
Lastly, my favorite character was the mother, but the story kind of screwed her in the end. I would have liked to see more of her and her story properly ended with the MC's failed mission.