In the real world, the Taisho Emperor had poor health from a young age, and died in 1926 after only ruling for 14 years, leaving his son Hirohito (the Showa Emperor) in power. The emperor's illness created a power vacuum that allowed the Diet and the political parties to gain more influence. the Taisho Era is often seen in history as a brief period of more democratic government, between the strict monarchy of the Meiji Era and the dominant militarism of the early Showa Era.
This story is set in an alternate 1936 where the Taisho emperor is still alive, and Japan is under a democratic government. In the 1930s in our world, far-right elements of the Japanese military continuously pressured the civilian government to adopt a more aggressive foreign policy. Several times, groups of officers attempted coups and assassinated high-ranking government officials, and by the late 1930s Japan was essentially fascist state.
A similar conflict plays out in the background of this anime, where mysterious forces are using cursed books to assassinate government officials who are seen as insufficiently patriotic. The main character, Kuze Tsugumi, gets mixed up in all this and joins an agency that tries to track down the cursed books. The main focuses of the show are her quest to unravel the conspiracy, and her relationships with the various men in the agency. It's all rather silly, but the connection to real-world history lends it a bit of depth.
There's also an undercurrent of social tension as traditions come into conflict with the modern world. Kuze is the daughter of an old aristocratic family, and her life undergoes a substantial change when she starts working as an investigator. The two other major female characters, the head of the book police and Kuze's friend the reporter, highlight how more roles are open to women in this new modern era. This is all mostly in the background and doesn't play that big a role in the story, but it does come up a few times.
Ultimately, this is a fun story about a girl trying to unravel a supernatural mystery with political intrigue. The presentation would make you think there'd be a greater romantic focus, but that's really more in the background, so the show isn't about an audience-insert character and her harem of sexy men. The characters have mostly stock personalities, but they have fun group interactions and some of their backstories develop in surprising ways. Kuze herself shows a good deal of courage, initiative, and commitment to protecting her new friends. The setting isn't taken too seriously, but it's not just for show and plays important roles in the main conflict and the themes.
If you like this kind of show, or if you're a sucker for alternate history, then you'll probably find something in this to enjoy.
