The Guardian Spirit of Baelheit first revealed to exist after Sagi's meeting in Mintaka with the man; where after Sagi leaves he begins to discuss with her in much the same way Sagi does to his Guardian Spirit. As revealed during Baelheit's explanation of his tragic past; he met and bonded with Daimon in Nekton- the shrine of spirits in Mira. It is she who provides him with the knowledge necessary to create Machina. The legends of the power to shape the destiny of the world give Baelheit a new meaning in life that would ultimately corrupt him to the point of deciding that the peace of the world depended on his abilities to destroy any connections humanity had to Wings of the Heart; even despite his ironic connection to the very representation of such a thing. Over the years of his continued descent into this corruption of idealistic goals they remain together despite her no longer believing that what he does is right, perhaps out of some form of duty and friendship and the hope that he was still able to change his ways before it was too late. Ultimately this does not happen and she finally refuses to give him her power as he faces Sagi, making a stand and doing her part in righting the wrongs she and her host had done. Daimon is seen a final time breaking her bond with Balheit in order to let him die peacefully in a shower of cherry blossom petals, just as she had appeared when they had first met.
Her name may be a reference to the Greek philosopher Socrates, who claimed that his decisions were influnced by an invisible being he called a "daimon." The word eventually came to be "demon" in English.