On Bayron City, a Pacific mega-float built over the world's only deposit of the energy mineral Orgonium, demonic intrusions called D-Hazards get cleaned up quietly by private military contractors. Shu Ogata runs one of the smallest of those PMCs, the perpetually broke I&S Office, with a single employee. That employee is Kisara, a centuries-old demon girl whose strength he tops up with a kiss, paid for in shavings of his own memory. When a job goes sideways, Shu calls in his ex-girlfriend Ayano Yugiri from the rival firm AAA, complicating both his contract with Kisara and his finances.