Otto

Despite her boyish looks, Otto is actually a girl and one of the last Numbers to be completed, along with Deed and Sette. Being a taciturn person makes hard for her to communicate with others. But due to their akin personalities, she and Deed share a strong bond that allows them a degree of silent mutual understanding. In the absence of any of her oldests sisters, Otto is the one who takes the leadership over the late generation Numbers.

Following her arrest, she is placed under the custody of the Saint Church for rehabilitation alongside Sein and Deed.

(Source: Wikipedia)