This is my theory but i believe the real mastermind behind the curtain is the healer. They didnt evenb showed us a proper conversation that she had with anyone but there is one scene i believe gave it away. The scene where newton got brainwashed. you can clearly see her evil face but it was shadowed by neumanss to distract the readers. Her ability is probably lets her not only heal wounds but change the way they work as well. so she used her ability firstly on neumanss to get the brain part to her side. I cannot say that I am 100 percent right . Because we did not see the healer in the "onii-chan's past" arc .Well atleast this theory can explain why neumanss is acting irrational like demonstrating their strength rather then using element of suprise to shake the world in an instant
well i think this would be interesting developments but what can I hope other than good plot twist