A world where notebooks exist, but not just any notebooks. If you write a name in these notebooks, that person will die. This is the world Death Note is set in.
After watching all 37 episodes of Death Note, I felt sad. Throughout this dark anime (in more ways than one) I felt a turmoil of emotions. Anger, Happiness, Sadness. I grew to love Light's character, even though I wanted to hate him. I enjoyed the rivalry between Light and L, and then later Light and Near. I was sad when L, Rem and Watari died. I hated characters like Demegawa.
But throughout Death Note, there were only two points that actually brought on extreme emotion, both of which were extreme sadness, as in I actually cried at those points. The first was Naomi's suicide. Just watching her walk off, after seeing that look on her face. That empty sadness. And watching the scenery changed into gallows. I just cried after watching that.
The other instance was Light's death at the very end of the anime. A slow death as the credits roll by, intercut with scenes implying Misa commiting suicide. The hopelessness of Light's situation. I really wanted to hate him. But I couldn't. I couldn't hold back the tears.