When the chant "Eko Eko Azarak" sounds something is bound to occur, be it within the town or the school!
A classic horror manga, Eko Eko Azarak follows the witch Misa Kuroi ("Black Mass" in Japanese), and the various horrors she encounters during her travels.
While relatively unknown outside of Japan the series was extremely well received domestically. It lasted for 19 volumes, spawned two sequels, an OVA, two TV series, six live action films and two video games.
Included one-shot:
Volume 19: Hitokui Ichizoku