Yokoshima drawing the mark on Mikami's forehead
Spirit Entrance Mark (霊の入口の印 Rei no Iriguchi no In, "Soul Window" in the fan translation) is a mark that is drawn on the forehead to allow a yūrei to possess a person. It only appeared in the pilot Gokuraku Mouja, where Yokoshima is tricked to draw the mark on Mikami's forehead.