Bleach 640 see’s Mayuri and Nemu (or Nemuri Nangou) have a moment as she’s ordered not to get herself killed for the fact that Mayuri may have already got feelings for her. While Pernida regenerates all his fingers, he reveals his Quincy abilities while also mentioning that he’s always been a Quincy. Pernida destroys Mayuri’s Bankai using his abilities.
Bleach 638 continues the battle between Mayuri vs Pernida, we see Pernida try to use his hands and nerves in order to manipulate inorganic material to catch Mayuri out, he does and forces Mayuri to explodes his armor revealing whats under his mask to be tube like hair and ears. Mayuri explodes Pernida’s pinky finger as a sample when it also comes to life.
Bleach 637 see’s the real identity of Pernida to be the Soul King’s Left Arm, compared to Ukitake’s Kamikake. While Mayuri battles Mayuri, he gets even more giddy and happy to see that he can experiment on his left arm as much as he wants. While this goes on, Nemu notices that Mayuri could possibly have changed.