The Warring States or Sengoku period of Japan was marked by intense and violent strife between the various domains of the main Japanese archipelago.
This is where "history" ends, and where human myths begin.
In order to subvert and defeat rival factions, warlords -- and sometimes even members of their families -- made blood contracts with powerful beings known as oni, who could do anything from gather intelligence, summon fire or water, or strike foes down with words alone. These oni demanded prices ranging from tributes of dolls to spiritual energy for their services; the most powerful of all devoured human sacrifices.
Toyotomi Hideyoshi, the second unifier of the Japanese domains, ordered the creation of a small corps of elite warriors to protect both himself and the capital of his Japan, Kyōto. This hidden society came to be known as the Urashichiken, and while it exists to this day, its numbers have dwindled to only three operatives and their boss, the reincarnation of Toyotomi Hidetsugu. The members of the Urashichiken now wage battle against bizarre creatures that lurk in the otherworldly spaces of the city.
However, Toyotomi Hidetsugu has become determined to enter a potentially-disastrous struggle with other reincarnations of Sengoku- and Tokugawa-period generals and their families: the struggle to locate the long-missing body of warlord Oda Nobunaga, in which is sealed the most powerful oni of all -- Dairokuten Maou.
Onto this scene of battle and intrigue arrives Chikahito Takamoto, a high school student from Tōkyō with a deep love of Japanese history. Due to his inexplicable spiritual alignment with wuji, or non-polarity, he stumbles into one of the otherwordly spaces of Kyōto just as the three members of the Urashichiken are about to destroy a gathering of monsters. Chikahito finds himself drawn to Hana, the designated warrior of the Urashichiken; as Hana too is aligned with wuji, a great rarity in the world, zie chooses to ensure that Chikahito will return to Kyōto one day, rather than simply have hir teammates Sakura and Tachibana erase his memories and send him off.
Later that year Chikahito indeed manages to return to Kyōto -- this time to stay, as a student at Nishijin Academy. Hana, Sakura, and Tachibana find him and allow him to live in the Urashichiken, where he ultimately becomes embroiled in the struggles between the oni-wielders.
Or: Hana, I don't think we're in Kyoto anymore!
CHAPTER 1: Chikahito and Hana
Or: It's a lion! Get in the kekkai!
CHAPTER 2: Hana and Urashichiken
Or: Ramen is not a universal constant.
CHAPTER 3: Hidetsugu and Oni
Or: Okay, let's be serious here.
CHAPTER 4: Nobunaga's Oni
Or: Why can't we all just get along?
CHAPTER 5: The Tokugawa Blood Contract
Or: I've always been dependent on the kindness of strangers.
CHAPTER 6: Tachibana, Sakura, and...
Or: Record of an Osaka Shopping Trip
CHAPTER 7: The Sanada Ten Braves
Or: Challenge and fighting and fighting the challenge toniiiiight!
CHAPTER 8: Yukimura's Power
Or: Digivolve...into Ultimate!
CHAPTER 9: Chikahito and Iemitsu
Or: "Always come back...alright?"
CHAPTER 10: Transfer Students
Or: This is going to be awkward.
CHAPTER 11: Masamune and Gracia
Or: A Foolishly Foolish Battle between Foolish Fools
CHAPTER 12: Kurikara
Or: The Japanese mafia needs to look into Nigemizu's tattoo artist.
CHAPTER 13: Hana and the Contract
Or: "I'm mad as hell, and I'm not going to take this anymore!"