死神界のタブー was the original title. タブー is tabuu so it is a loanword from English. I double checked what the etymology of the word was because I was curious and it apparently comes from tapu from Tongan, a language spoken on the island of Tonga in Polynesia.

May 18th, 2011. Author's note:
"Q: Is there a specific song you listen to when you want to cheer yourself up?
A: Arashi."