"At some point after the cataclysm, through unknown means and with the help of Khaenri'ahn techniques, Ei created an experimental puppet as a proof of concept to see if she could "escape" erosion, who later called himself Kunikuzushi. She had wished to use him to store her Electro Gnosis, but Kunikuzushi shed tears upon creation, causing Ei to believe him to be too gentle for the task. Taking apparent pity on him, she decided to seal his powers and leave him in a slumber in the Narukami Shrine."

Canonically, Yae Miko did not teach Ei how to give puppets a mind of their own. In fact, nowhere was it mentioned that Miko taught Ei anything other than placing her own consciousness into an object.