The protagonist of the series, which is set in the Heian era, is Abe no Masahiro, the grandson of the great onmyōji, Abe no Seimei, who passed his teachings on to his grandson. Unfortunately, Masahiro has lost his sixth sense and with it the ability to see spirits. Masahiro constantly feels overshadowed by his grandfather's fame. One day, Masahiro meets a fox-like creature which he names Mokkun who shows him his true potential powers after fighting a demon. Mokkun is actually Tōda, who prefers to be called Guren. He is one of the twelve shikigami called the Shinshō who has pledged his loyalty to Seimei and is helping Masahiro to surpass his grandfather. Masahiro's dream to surpass his grandfather will not be realised as easily as he hopes. Not only does he have to convince the other Shinshō that he is Seimei's true successor, he must also increase his power in order to stop demons coming from China, the other parts of Japan and the Underworld. In addition to this he has to deal with the schemes of rival onmyōji who want to destroy Japan not to mention keeping his promise to protect Princess Akiko of the Fujiwara clan.