For

Fo
(フォー) Seiyū: Mina Tominaga

Fo is the guardian deity of the Black Order's Asian Branch, sealed by Bak's great-grandfather. Although she is not a human, she often takes on a humanoid form to talk with others. Fo found Allen's body after his attack by Tyki Mikk and took him the headquarters of Asia Branch. She has a "tough-love" attitude, particularly towards Allen. While she was training Allen in an attempt to bring back his Innocence, she would attack without mercy with the hope that the Exorcist would activate his Innocence. When Allen was feeling down, she would appear to him as someone else (eg: Lou Fa (this way she could show her soft side without Allen knowing). During their training, Allen and Fo developed a unique bond as friends.

She also shares a very strong bond with Bak even though she loves to tease him. She can manipulate her form in order to gain axe hands or to copy someone's appearance. She is also capable of communicating telepathically with others. The Headquarters of the Asian Branch is protected by a very strong barrier created by Fo (who is the "entrance" of the barrier). Inside the shell, she is very caring and is willing to give her life for the sake of those she loves. She took Allen's form to face the Level 3 Akuma, in order to buy the real Allen time. Just before they began to fight, she said to herself "Bye bye, Bak." Allen refused to let the sacrifice happen and finally convinced Bak to let him go back for her. Bak rescued Fo while Allen confronted the Level 3 and defeated it with the newly activated Crown Clown. She was hurt badly by the ark as it appeared right under where she stood and created a hole in her bdy where her heart should be, but she healed afterwards.

Powers and abilities
Body Manipulation: Fou is able to transform parts of her body into different objects, usually weapons, or even change her whole appearance to mimic someone else’s. She showed this power while training Allen Walker to regain his Innocence by transforming her hands in blade weapons and later during the Akuma Level 3 Thread's invasion of the Asian Branch by taking on Allen's appearance so she could fool

Remote Viewing: Fou can use the deity symbols within the Asian headquarters to view other locations without having to be there personally.

Telepathic communication: Fou is shown to be able to communicate with other with her mind.

Barrier Creation: The headquarters of the Asian Branch is protected by a powerful barrier Fou has created and maintains, which has done so for over a hundred years. Fou herself is the entrance into the barrier. Such is it's strength the Level 3 Akuma, Thread, had to use Noah's Ark's doors to bypass the barrier and enter into the headquarters. Presumably after Thread's defeat, the barrier was instated. Whether a means has been found by the Asian Branch to block further such intrusions is unknown at this time.

Expert Combatant: Fou is show to be stronger, faster and tougher then a regular human, as given her supernatural origins. However, despite this, she is no match for a level 3 Akuma or most likely for a general level exorcist (This is hypothetical as she has not battled a general level exorcist. However, given Allen's newly awakened innocence crown clown was able to defeat a level three easily when Fou had been losing badly against it, it is more than likely she would be no match for a general level fighter).

Trivia

 * Fou seems to like Bak. As hinted in one of the post credits, calling Bak as Stupid Bak(Baka-baku), saying that she likes him and eventually adding that she is only joking.