Nageku Shinigami can be summarized in one sentence:
You read it, you cry, you love it.
It's a oneshot, so going into detail would spoil much of it. But I can say, it has a bittersweet story that touches the heart.
If you have a bit time, read it, it is only one chapter. I'm sure you won't regret it.

Please forgive me for writing such a short review.