My Master Is the Ghost King, and He Stole the Copy?

【Power fantasy + no romance or ambiguous relationships + supernatural mystery dungeons】 “Master, is there really no more dignified way to get ghost energy?” asked the black-robed young man as he dug a grave. “Not at the moment,” the white-robed young man replied calmly, watching his disciple dig from outside the pit. The next morning, when two dungeon marks appeared, the pair's grave-digging routine finally came to an end. Content warnings: 1. The master is not human and has no absolute concept of good and evil. He simply does what he wants. 2. The disciple retains some humanity, but his master's teachings have warped his perception. 3. There is no romantic tension. The master and disciple are more like teacher and student, or father and son.