Set in the early Taisho period (1912–1926), the narrative unfolds in a world where Vampire Subjugation Squads are elite units deployed by the Shinto Association to eradicate vampire infestations. Operating under the cover of night, these squads don traditional Tonbi Coats, or Japanese Inverness Capes, which serve to conceal their specialized tools and weaponry. This attire ensures their activities remain discreet, preserving the veil of normalcy and preventing public panic while they conduct their perilous missions in the shadows.