Perimeter

Perimeter or "Maai" (the space between oneself and the opponent). This technique forms a field that the samurai generates around him/her-self through the use of their ki. If a person enters this field, the samurai will know when that person entered and where that person is even while sleep It can be said that it's like the samurai is standing in a pond of water or on a spider's web. The moment a person steps into that pond or on that web, the samurai is alerted due to the ripples (pool) or vibrations (web) created. Only other master warrior samurai and newborn babies can enter this field without being noticed by the samurai. It can be compared to (One Piece) Kenbunshoku Haki.