A total of four different sites have been known as Karasumori, each with one or more Kekkaishi serving as its guardian(s). Each location features a central building (usually a castle) where the last Karasumori resides in isolation, hidden away to reduce the negative impact of his great power upon humanity. But such power is not easily contained, and Ayakashi who hunger for it are always near.
Home of the ancient Karasumori Clan, and plagued by the constant presence of Ayakashi. Tokimori Hazama was hired to deal with the problem, becoming the first Kekkaishi to protect Karasumori. However, he was driven away because of his relationship with Princess Tsukikage, and Tokimori's quest for revenge resulted in him imbuing his unborn son with a cursed power that destroyed the entire clan. In order to honor Tsukikage's final wish, Tokimori took the boy away to raise him in solitude and safety, creating the legend of Karasumori to conceal the truth about their son.
Chushinmaru's Black Castle
Tokimori eventually obtained ownership of a forest, and used the land's power to create a black castle in an underground Shinkai, where his son Chushinmaru Karasumori was meant to remain sealed. However, Tokimori's power was waning, and he could not completely seal his son. Consequently, Ayakashi were still drawn to the boy's power, so Tokimori passed on the Kekkaishi profession to ability users from the Shadow Organization, using the false legend to convince them to become the land's protectors. Kekkaishi would continue to guard the land for 400 years, though bloody feuds over who was Tokimori's rightful heir would leave only two clans: the Sumimura and Yukimura. Karasumori Academy was eventually built on top of the site. Sumiko Sumimura searched the world for a suitable Shinyuuchi to completely seal Chushinmaru within, choosing Hakuma and leading the team that finally extracted Chushinmaru from the site. Without Chushinmaru inside, the Shinkai containing the castle collapses.
An abandoned house temporarily serves as the home of Chushinmaru after leaving his castle. As any place he resides essentially becomes the new Karasumori castle, Ayakashi began to swarm around it in large numbers, making it necessary for Yoshimori Sumimura and Sumiko's Shikigami clone to protect it. Yoshimori later begins his Shinkai training under Tokimori there as well.
Castle-Town at Hakuma
Yoshimori uses Chushinmaru's power to create an enormous Shinkai, placing a sprawling castle-town filled with playmates, including a copy of nearly everyone Yoshimori has met during his time as a Kekkaishi. However, the Shinkai can only be activated from the inside, meaning a Kekkaishi must remain for the rest of their life.  Sumiko chooses to seal it for Yoshimori, and completes the task.
- ↑ Kekkaishi manga, Chapter 313, page 3
- ↑ Kekkaishi manga, Chapter 313, pages 15-17
- ↑ Kekkaishi manga, Chapter 314, page 14
- ↑ Kekkaishi manga, Chapter 314, page 17
- ↑ Kekkaishi manga, Chapter 315, page 2
- ↑ Kekkaishi manga, Chapter 316, pages 4-5
- ↑ Kekkaishi manga, Chapter 316, page 6-9
- ↑ Kekkaishi manga, Chapter 316, page 13
- ↑ Kekkaishi Manga chapter 344