Area Defense

Area Defense is a device set up in some regions that inhibits the formation of Caves over a wide area. It does this by broadcasting radio waves which have a jamming effect. This makes it more difficult for the Huge to attack the area in force, though they can still do so by traveling in the normal fashion, without the use of Caves.

Not all locations are suitable for Area Defense. According to Miliam Hildegard von Guropius, such a system would have little effect if installed in the geographical vicinity of Yurigaoka Girls' Academy, no matter how powerful the broadcasts were.

Places that are known to have effective Area Defense systems are Tokyo, Japan and Sasebo, Japan. Tokyo's Area Defense system is the strongest one in Japan. Ho Chi Minh City in Vietnam also has one, but it did not stop a large-scale incursion from happening there several years ago.