Yōka Murase (村瀬 陽香 Murase Yōka)
A young woman with the ability to apply an 'erase' capability to anything. The requirement is she must first state the target of the ability, the object/phenomena to be 'erased', and make physical contact with the target. For example, stating the target to be her hands and the object to be erased as a wall would apply the ability to her hands and enable her to erase a part of a wall with it.
Her brother was a member of the Administration Bureau and is now deceased due to unmentioned circumstances, leading Yoka to swear revenge on the Administration Bureau for being involved in the events regarding her brother's death.
At first, Youka threatened Kei to do as she wanted from saving a cat to joining forces in order to take down the Bureau on the week they first met. Soon, Kei fights her and traumatizes her.
From then on, Youka co-operates with his requests and becomes trusted comrades.