Despite his prestigious lineage as the grandson of the renowned onmyouji, Abe no Seimei, Masahiro lacks the ability to perceive supernatural entities, a crucial skill for his profession. Due to this limitation, he must contemplate pursuing a different career path. However, Masahiro's fate changes unexpectedly when he encounters a peculiar mononoke, whom he names Mokkun. After fighting a demon with Mokkun at his side, Masahiro discovers his true abilities. With Mokkun's guidance, he sets out on a journey to become the most influential onmyouji.