Kekkai is a spiritual (or Shinto) Japanese word. It is a kind of barrier protected with spiritual power. My charcoal master is promoting “Charcoal Kekkai”. He is saying that it will make the energy higher if you put some charcoal at four corners of any space. If you have somebody lying sick on the bed, just put charcoal at the four corners of the bed. If you have a bad feeling in your room, put the charcoal at the corners. It will change the energy. Again, there is no scientific basis but many people are finding the difference.