A Certain Magical Index Episode 21 English Subbed Episode Title:Identity Unknown (Counter Stop).Episode Description:After the summer break, Töma returns to school and learns Komoe is researching about AIM (An Involuntary Movement), a diffusion field of power that espers emit. Index is sent away by Komoe when she arrived at Töma's class and Aisa introduces herself as the new transfer student. She runs into another transfer student named Hyöka Kazakiri and befriends her...