[DeepL Translation - needs review] Volume 1: The year is 1926. There were those who protected the Imperial City from the demonic beings that lurked in the shadows of everyday life. The young Devil Summoner, Kuzuha Raido XIV, who works for the Narumi Detective Agency, is one of them. Despite its glittering exterior, the Imperial Capital is a whirlpool of various desires. As Raidou and his friends solve strange cases, an awe-inspiring presence soon looms in their vicinity. ...... Darkness now ...
The manga is based on the Devil Summoner: Raidou Kuzunoha video game series and takes part after the second game. Knowledge of the games isn't necessary to read the manga, as the main cast gets properly introduced.
The story takes place in the 1930s. The protagonist is a devil summoner that has inherited the title of "Raidou Kuzunoha". He works at the Narumi Detective Agency and is charged with protecting the capital against supernatural threats.
The difficulty varies. Some characters are easy to understand while others use more archaic Japanese. There are also characters that speak Kansai-ben, the demons have various speaking tics and of course there's supernatural/mythological vocabulary, so this is definitely not suited for beginners. For the most part, especially the earlier volumes, I felt like there was usually one of the easier to understand characters present, but that doesn't hold true throughout the entire series. Still, it has everything from N3 to (what I think is) N1+ Japanese, so if you feel like challenging yourself, check it out.