Isoko "A" Anjou
About
It is confirmed that she actually was acting under a nickname "A" and gave Mahou Shoujo sticks to random people. After Nana made some agreement with Misumi, Anjou was captured by him and kept at his house secret room.
It is later explained in Mahou Shoujo Site Sept that Nana got some agreement against the site with Anjou before she even became an admin.