Inside a human body, when humans evolve into Second-Level Black Iron Warriors, five "doors" emerge within the body, each sealing off a different part. Each time a "door" is opened, an additional part undergoes a mutation and evolution, thereby elevating their realm by one level. When all five "doors" are completely opened, one evolves into a Seventh Order Black Iron Warrior. At this point, all parts of the body have fully evolved and mutated and there are no more "doors" to open inside the body. Every person then faces the same conundrum: which path should they take next?
Once every part of the body has mutated and fully evolved, reaching the peak of the Black Iron realm, how does one continue to break through? Ouyang Nuo was stuck here, unable to break through. In fact, many powerful individuals in this world were trapped at this stage, unable to breakthrough for their entire lives.
