Oni wa Tamayura, Teito ni You

Akito Jinguji, a soldier in the Imperial Army who hunts down supernatural beings, is feared by the people as a ruthless warrior. He receives an order to hunt down a demon known as the "Leader of a Thousand Demons"—Arashika. Arashika possesses unparalleled beauty and immense power, causing chaos throughout the Imperial Capital, yet she also whimsically helps people, making her somehow endearing. Akito finds himself unconsciously drawn to Arashika, and begins to agonize over whether hunting this demon is the right thing to do. While wavering, Akito tries to fulfill his duty as a soldier. But the method to defeat the demon requires Akito's own life…!? A solitary soldier and a beautiful demon. The chase through the cherry blossom-filled Imperial Capital begins here! (Source: Kadokawa, translated)