Cruel Blood Oath is a large sword in NieR: Automata.
"A black katana kept by warrior monks of the East."
- "This warrior's sword has been stained jet black with the blood of years of conflict.
- In the underground portion of the first desert area after the Desert: Camp access point. It is placed behind an iron door, which can be unlocked by hacking it with 9S.
- Level 1
- "I'll never forget the time we met. I knew ours was a love that would last for eternity."
- Level 2
- "But even when by his side, his feelings were a mystery. It was painful not to know what he was thinking. So painful."
- Level 3
- "When I was close, I hurt him. Yet being distant hurt him more."
- Level 4
- "I finally found my place in life. A place where I am as close as possible, yet eternally distant."