Getting Joy-instantkill through the arm-transplantation? Ok. Just staple on Etou´s hand to get her strenght and have full control over her hand? Bit weird, but well, may as well accept that. But when the holy fuck did Hayashi turn into a power-vampire that could just take in other peoples bloodlust powers at will by consuming part of their body?! And didnt the doctor that gave her the arm say that this method bears a high risk of dying / shortening your life? Taking in so many powers in such a short time should have killed her.