Young detective Sonia Summers has been transferred to the outskirts of the port city Libra after stirring up trouble with her superiors. Libra is separated into two sectors—”the Upper”, the center of wealth and politics, and “the Outside”. The Outside is home to crime, corruption, and curious incidents involving monstrosities or youkai. Each case that Sonia works on seems to implicate the involvement of these mysterious creatures.
Sonia crosses paths with three peculiar humanoid youkai — Bem, Bela and Belo — who seek to protect humans and fight against the evil youkai that terrorize them. Living as “Youkai-Ningen,” they are excluded by other youkai for their human-like lifestyles, and rejected and hurt by humans when they reveal their true forms.
Despite the hardships they face, these three Youkai-Ningen secretly live among humans, continuing to pursue their dreams of one day becoming human as well.
Despite being burdened with crippling debt to the morose Haruitsuki Abeno, Hanae Ashiya has come to enjoy his job as an exorcist. His ability to communicate with youkai has given him a sense of responsibility regarding the magical creatures, and he continues to work hard to send them to their true home in the Underworld.
As Ashiya’s life finally stabilizes, the youkai threaten to upset it once again. Knowledge of his existence has begun to spread, and not everyone is happy to have a human working for the Mononokean, the interdimensional tea room. But one day, a simple visit to the Underworld draws the attention of those in power, and Ashiya soon learns that not every youkai is willing to go along with Abeno’s plans.
The start of Hanae Ashiya’s high school career has not been easy—he has spent all of the first week in the infirmary, and his inexplicable condition is only getting worse. The cause of his torment is the mysterious fuzzy creature that has attached itself to him ever since he stumbled upon it the day before school began.
As his health continues to decline and the creature grows in size, Hanae comes across a flyer advertising an exorcist who expels youkai. Desperate and with nothing left to lose, he calls the number and is led to the Mononokean, a tea room which suddenly appears next to the infirmary. A morose-sounding man, Haruitsuki Abeno, reluctantly helps Hanae but demands payment afterward. Much to Hanae’s dismay, he cannot afford the fee and must become an employee at the Mononokean to work off his debt. And to make things worse, his new boss is actually one of his classmates. If Hanae ever hopes to settle his debt, he must work together with Abeno to guide a variety of dangerous, strange, and interesting youkai back to the Underworld.
When his clan is wiped out by a beautiful demon, young Taikobo finds himself in charge of the mysterious Houshin Project. Its mission: find all immortals living in the human world and seal them away forever. But who do you trust—and whose side are you really on—when you’ve been trained to hunt demons by a demon?
Female college student Aoi inherited her deceased grandfather’s ability to see ayakashi. One day, while Aoi is feeding some ayakashi, a demon appears! He declares that Aoi’s grandfather owed a great debt, and as compensation, Aoi must marry the demon! Aoi refuses, and decides to pay off the debt by working.
High schooler Nanami Momozono has quite a few problems of late, beginning with her absentee father being in such extreme debt that they lose everything. Downtrodden and homeless, she runs into a man being harassed by a dog. After helping him, she explains her situation, and to her surprise, he offers her his home in gratitude. But when she discovers that said home is a rundown shrine, she tries to leave; however, she is caught by two shrine spirits and a fox familiar named Tomoe. They mistake her for the man Nanami rescued—the land god of the shrine, Mikage. Realizing that Mikage must have sent her there as a replacement god, Tomoe leaves abruptly, refusing to serve a human.
Rather than going back to being homeless, Nanami immerses herself in her divine duties. But if she must keep things running smoothly, she will need the help of a certain hot-headed fox. In her fumbling attempt to seek out Tomoe, she lands in trouble and ends up sealing a contract with him. Now the two must traverse the path of godhood together as god and familiar; but it will not be easy, for new threats arise in the form of a youkai who wants to devour the girl, a snake that wants to marry her, and Nanami’s own unexpected feelings for her new familiar.
Yin and Ning are two sisters who have been wandering the land together ever since their village was destroyed by the villainous Taibai Empire. Their childhood friend, Zhao, has been enslaved by the Taibai himself, and uses his brilliance at tinkering and inventing to get by as a slave to the Empire’s whims. One day, Yin accidentally discovers a legendary sword, which grants her fantastic abilities in combat, and allows her to summon a mystical, mechanical fox spirit named Yun, who is sworn to fight by her side. Meanwhile, Zhao is making fast friends with a mysterious young girl who just may hold a great amount of power within the Taibai Empire. As Zhao and the Fu sisters find themselves increasingly caught up in the Empire’s battle for supremacy over the land, it will take all of the magic and might that the budding resistance armies can muster to turn the tide of war once and for all.
The series is set during the Edo period, in the Fukagawa ward of old Edo (present-day Tokyo). Because the area is prone to fire and flooding, residents rent everyday items like pots, futons, and clothing from shops instead of purchasing them, so as not to impede them when they flee. Obeni and Seiji, an older sister and younger brother, run one such rental shop called Izumoya. However, mixed in with their inventory are tsukumogami, objects that have turned into spirits after a hundred years of existence. The siblings sometimes lend these sentient items to customers. Both Obeni and Seiji can see and talk to these spirits, and other tsukumogami often come to the store after hearing of the famed siblings.
Ushio Aotsuki is a stubborn middle school student and son of an eccentric temple priest who goes about life without care for his father’s claims regarding otherworldly monsters known as youkai. However, as he is tending to the temple while his father is away on work, his chores lead him to a shocking discovery: in the basement he finds a menacing youkai impaled by the fabled Beast Spear.
The beast in question is Tora, infamous for his destructive power, who tries to coerce Ushio into releasing him from his five hundred year seal. Ushio puts no trust in his words and refuses to set him free. But when a sudden youkai outbreak puts his friends and home in danger, he is left with no choice but to rely on Tora, his only insurance being the ancient spear if he gets out of hand.
Ushio and Tora’s meeting is only the beginning of the unlikely duo’s journey into the depths of the spiritual realm. With the legendary Beast Spear in his hands, Ushio will find out just how real and threatening the world of the supernatural can be.