If you liked the A Tree of Palme anime, the Anime-Planet community thinks you'd like:
In the not-so-distant future, mankind is at war with itself. The lives of Chise and Shuu are torn apart when Chise is chosen to become the ultimate weapon to fight for Japan against their enemies. Death, sadness, and the hardships of love accompany Sai Kano in its grim look at war and its consequences.
The pacing is a bit slow, but the content is intense with an extremely dramatic feel for events. I can't say A Tree of Palme or Saikano will leave you with a "feel-good" ending. You'll find yourself watching complicated relationships, listening to somber music, and being amazed at the artistic imagination (creativity) through their animation.