Fridge / Disgaea 4: A Promise Unforgotten

• Technically, the whole series takes place in the far future and once we learn that apparently humanity has become so malicious that it's become one of the seven planets that needs to be destroyed tells you just how bad the world has become.
  • Not quite. Recall that there are multiple human worlds. The one from the 1st game was more advanced than the one in 4. The third game’s human world was about the same tech level as the one in 4. This human world is just an exceptionally nasty one.

• Judge Nemo's hatred is apparently the most powerful on the planet, and is what keeps him alive after four hundred years.

• Even if he does drink Vulcanus's blood, he is not breaking his vow to never drink human blood ever again. She's no longer human, being a angel. He is however able to fulfil the promise to only drink Artina's blood after making her feel fear.