Over a thousand years ago, during the Heian period of Japanese history, politics in the capital city of Heiankyo, present-day Kyoto, center on the Yin Yang Bureau, whose school trains the yin yang masters who defend the city from curses and other malevolent spells. Students, called "apprentices," seek to become full-fledged yin yang masters and thus win higher government positions. But Abe no Seimei, while he is brilliant at the magic arts, is an eccentric figure who does not seek friends, and is therefore shunned by his fellow students. Hiromasa, of the aristocratic Minamoto clan, comes to the Yin Yang Bureau. He wants Seimei to minister to Yoshiko, an imperial princess returned from girlhood service as the Emperor's representative at the Grand Shrine of Ise, and whose nights are now tormented by strange visions. In spite of personality conflicts between them, Seimei and Hiromasa proceed with their investigations, but following the mysterious death of another apprentice they are caught up in a major incident that threatens all Heiankyo. The young Abe no Seimei must stand against a vast conspiracy and the powerful curse it has engendered.