Hei An Ji Dai is a board game about onmyoji in Heian era of Japan. In the Heian era of Japan, the monsters who were supposed to be in the underworld appeared in the world and created all kinds of disturbances to bring disaster to the world. There is a kind of power called "onmyoji" in the world. They can drive runes, chant incantations, slave demons, and send them as "shikigami". Yin Yang teachers use their own abilities to maintain the balance between yin and Yang.