Hungry Ghost

No idea, but guessing it is about drugs is probably not a wild guess considering it's SoB...

imao,this song has several subtle references tot Taoism, & how it deals with (what they call) hungry ghosts (èguǐ)

i think this song is about onryo (vengeful spirits in japanese folklore).

"lying there inside of a tomb, like lying there in your mothers womb" "written bare in blood that were red" - their murder and being reborn in death.

"we're following the book of the dead" - this part is the most open to interpretation:

• it may mean an unwritten law, i.e "an eye for an eye" or it could mean the "cycle" of vengeance, maybe they don't do what they do by choice.
• in the "grudge" movies, kayako, an onryo, had a diary, and it plays an important part in both films, and it's the reason she and her son are killed (by her husband, who becomes her first victim and another part of the curse).
• a long shot, but it could be referencing the tibetan book of the dead (bardo thodol), as it details the experience of the afterlife, and what happens to your consciousness, it could mean taking that journey.

"feed the hungry ghost" "all we are looking/searching for is life" - the spirits consuming a soul/killing whoever they encounter to survive and sustain the curse.