Douki-chan is a respectable office worker with one goal: to seduce her coworker Douki-kun. Unfortunately, this proves to be easier said than done, as her plans are constantly thwarted by Kouhai-chan and Senpai-san—her two love rivals who will stop at nothing to gain the affection of their beloved colleague first. Douki-chan will need all the luck she can get to surpass her competition and win Douki-kun's heart.

Takuma Hirose is a blind young male high school student, though the cause for his blindness is undetermined. In order to heal his medical condition, he is sent to live in a village with his uncle. There, he meets several girls, three of which stand out more than any of the others. They are Hayami Kohinata, Hinata Kangura, and Otoha. Otoha temporarily heals his blindness and Hirose uses his sight to help others. He finds out that, for some reason, Hayami Kohinata is hated in the village, and he tries his best to help her out. Meanwhile, many sad secrets unfold in the village...

In the 11th year of the Meiji Era, the end of the samurai shogunate and the prohibition of swords has left Japan with lasting scars. Displeased by these recent changes, many former samurai plot against the new government, inciting a wave of bloodshed. To counter this movement, the government constructs a colossal prison in the middle of Lake Biwa. Unofficially assigned to help the police arrest criminals, Tenka Kumou also serves as a ferryman to the Lake Biwa prison with the help of his two younger siblings: the ambitious Soramaru and the enthusiastic Chuutarou. Together with the former Fuma ninja Shirasu Kinjou, the Kumou brothers live a frugal and joyful life mostly dedicated to studying and training. However, behind this relatively uneventful daily routine, the specter of the Orochi curse is starting to spread its shadow over the city of Oumi. According to legend, every three hundred years, Orochi reincarnates in a human vessel—and it is believed that this is the harbinger of an imminent catastrophe. As various groups clash in search of Orochi's vessel, some aim to seal the curse, while others have darker plans in motion.

In ancient times, some witches married their familiars, who had taken human form, giving birth to a lineage of ogres. One such ogre is Morihito Otogi, who while appearing completely human, still retains the inhuman strength of his bloodline. Nico Wakatsuki is a young witch and Morihito's childhood friend, but as part of her education, she had to go to the Witches' Holy Land to train and part ways with Morihito. Years later, just before Morihito's first year of high school, Nico returns home with one goal in mind: to claim him as her familiar. While most witches choose a cat or a bat, Nico has her heart set on Morihito in more ways than one. Although seemingly oblivious to her true feelings, Morihito and Nico end up living together under the same roof with both of Morihito's parents elsewhere. While reluctant at first, Morihito accepts his new role, determined to help Nico seamlessly fit back in with human society and protect her from fated disaster.