It was found that, because this block corresponded to the kimon (the northeastern (unlucky) direction) of Toji-Temple which had been granted to Kobo Daishi (Kukai), Kukai sculpted a Fudo-son image out of a stone possessing spiritual force that he had found, and buried the image there so that it could not be seen.
これは、当該の区画が古くは弘法大師空海が賜った東寺の鬼門にあたり、空海自身が発見した霊力ある石に不動尊像を掘り付け、人目に触れぬよう埋めたものだと判った。