Onmyouji tells the story of renowned onmyouji Abe no Seimei, who meets and befriends the straightforward court noble Minamoto no Hiromasa. Together, they deal with strange cases in the Heian capital surrounding demons and curses.

On the surface, Nana, Kai, and Chiwa seem like typical office workers, but in reality, their everyday lives are spiced up by the bizarre situations they constantly encounter. Joined by their friend and self-proclaimed idol Kaeru, the trio attempts to go through their daily routine while facing the difficulties of being an adult.

After being defeated by the leader of the Beimu clan, Mount Xuandu's chief disciple Shen Qiao falls off a cliff and nearly dies from his injuries. Unfortunately, the ruthless Cleansing Moon sect leader Yan Wushi, known for his cunning and skills, chances upon him and comes up with a sinister plan: turn the benevolent disciple into a vengeful cultivator who could one day become a worthy rival. Shen Qiao is thrown headfirst into a world of betrayal and deception, contrasting with his once-strong beliefs that good could exist in everyone. As he encounters further hardships that push him to his wits' end, Shen Qiao is faced with the decision of continuing to uphold his kind nature—despite the cruel reality he has been shown—or giving in to the deceitful scheme of the spiteful Yan Wushi.

Since the beginning of Earth's history, angels from the planet Eden have been carefully monitoring the behavior of its inhabitants, whom they call Earthians. Chihaya and Kagetsuya are two agents sent from Eden to assess the positive and negative aspects of the Earthians' nature. Despite the orders Chihaya was given by his home planet, he frequently ends up entangled in Earthian affairs, much to Kagetsuya's annoyance. Meanwhile, as Chihaya tries to understand the origin of his strange black wings, he uncovers one mystery after another.