Musubi is one of the Shiko-Me demons, or according to herself, she is the only Shiko-Me. In a battle long ago Musubi was defeated by one of Izaname, Queen of Death and What Comes After, sons and forced to enter their service.
She is chosen by Susano-O to kill Lucifer Morningstar as he had entered their realm, where he would be mortal, in search of his wings. Musubi initially appears as a human-looking geisha who bathes and massages Lucifer while making small talk before he angers her. Having turned into her own shape, with a humanoid torso mounted on the body of a scorpion, she threatens to kill him before he offers her a way out of the slavery she lives in and allows him to behead her.
Later, Lucifer resurrects her as promised and tasks her to defend his gate into the Void beyond Creation which she gladly accepts, even if she knows she has to stand alone against the host of Heaven.
Not long after Amenadiel of the Thrones leads Heavens army against Lux and the portal, with the intent of gaining control of it, since they couldnt destroy it without destroying Creation itself. Musubi ambushes them at the gate and kills many of them before Amenadiel personally intervenes and beheads her again.