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The Sensing Barrier is a giant, dome-shaped barrier placed over a designated area. The barrier is not visible to the standard eye; when viewed with certain dōjutsu, it can be seen that there is a design of several circles which have the kanji for boundary (界), and barrier (結界, kekkai) inscribed in them. When linked with a Sensing Water Sphere, all unauthorized passage in and out of the barrier can be detected and pinpointed.
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