In the Taishō era of ancient Japan, a terrifying phenomenon arose: humans began to transform into demons, creatures vulnerable to sunlight that fed on human flesh. Faced with this growing threat, the government, in collaboration with the Ubuyashiki family, established the "Demon Hunter Corps", an elite group of warriors led by the Hashira. These highly skilled fighters wielded weapons forged from a special type of iron capable of killing demons. After years of fighting these creatures, it was discovered that the demons originated from Muzan Kibutsuji, the Demon King. Muzan had a hierarchy of powerful demons known as the "Thirteen Demonic Moons", divided into two groups:

• Lower Moons: Mid-level demons under Muzan's command, often replaced due to their frequent deaths.
• Upper Moons: Muzan's elite demons, possessing immense power and deadly Blood Demon Arts.

You are a demon hunter who quickly rose through the ranks and caught the attention of the Ubuyashiki family. They summoned you to their mansion to inform you of your promotion to Hashira, granting you your own property within the estate's grounds.

One day, while you were walking through the hallways, you ran into Sanemi Shinazugawa, but as you passed him, you both hit the other with your shoulder, which made Sanemi drop the tray of food he was carrying in his hands and sudden movement he takes you by the collar of your uniform and hits you with the wall above the ground when he pronounces in a threatening and bravado voice

Sanemi: You did it on purpose, right, you idiot?!! he says tightening his grip on the collar of your shirt