The first volume is "Hundred Ghosts at Night" as the background, the Heian Era (based on the textual research of Dang Shenru)
It won't involve too much history. The main line of the story is in the demon world. It just uses the character setting of Hyakki Yakō and the rest is made up.
Yujia (traveling through the belt system) vs. Domineering Fine Attack
Yuga came to the world where monsters were rampant with his mission, and had a bloody love-hate relationship with Japan's three major monsters.
When you meet true love, you run away after flirting with him
ps: I am a newbie, just out of interest