The Serpent's Eye (蛇の目, Ja no Me) is a pattern used by a secret group within The Shadow Organization, who are, when mentioned at all, also referred to by that name. They typically have little or no contact with anyone outside their group, both to maintain secrecy and protect their knowledge. The group recruits those who can predict the future (most of whom appear to be young girls). One member is selected to become the "Miko who delves into the abyss," effectively making her the group's leader and primary seer. However, the Abyss Watcher is forbidden to leave the mansion where the group resides, and her legs appear to be shackled to accomplish this. Her life is literally devoted to this position, because viewing or even sharing visions of the future has been known to shorten a person's life considerably.
Nozomi, the last Abyss Watcher, sent her subordinate Saki to all of the remaining sacred grounds, carrying a warning that a bloody future was in store for the Shadow Organization, and that Karasumori would be a key playing field for these events. Though Saki's mission was successful, she reported back to find that Nozomi had taken her own life. Saki was one of the candidates for the next Abyss Watcher, but realized that Nozomi had trusted her with such an important task because she was the only Miko so fascinated by the outside world that she repeatedly left the mansion against orders. Saki left the group shortly before it was dismantled, deciding that it was more important for her to remain mobile.
The group is called the Bull's Eye in the Viz English translation.