An omniscient narration introduces the Hell Correspondence, a supernatural service accessible only at midnight to those consumed by intense grudges. It details the process: submitting a target's name summons Enma Ai, who offers a straw doll bound by a red string. Pulling that string consigns the target to hell but irrevocably binds the user's soul to the same fate upon natural death, marked by a black crest on their chest. This narration evolves beyond simple exposition, framing each episode with thematic gravity. It often opens with poetic reflections on human suffering, fate, and vengeance's cyclical nature, describing encounters governed by fate where "cursed flowers bloom – pitiful and frail; lost in their anger, their sorrow, their tears." It directly challenges the audience, questioning if they too would seek such revenge, reinforcing the core moral dilemma. Specific phrases recur ritualistically. When Ai manifests, the narration intones: "O pitiful shadow bound in darkness, looking down upon people and causing them pain, a soul drowned in sinful karma... Would you like to see your death once?" After the string is pulled, it declares, "This grudge will send you to hell" or variations like "Your grievance shall be avenged," cementing the irreversible consequence. Later seasons adapt these phrases for successors like Michiru, altering wording to reflect their distinct perspectives while preserving the core structure. The narration expands to contextualize the Hell Correspondence's broader mechanics. It references the "Eternal Twilight," Ai's realm where contracts are made, and alludes to unseen governing forces like the Master of Hell, who enforces the rules binding her. It frames the escalating moral ambiguity of later seasons, shifting from scenarios with clear victims and perpetrators to those where blame is shared, reflecting a deepening exploration of revenge's corrosive nature. Across all official media, including manga anthologies and live-action adaptations, the narration maintains its core function: setting the tone, explaining the rules, and posing ethical questions. While manga may feature slight variations in story details or artistic style, the narration's purpose and key phrases remain consistent, anchoring the anthology format. Live-action adaptations similarly retain the narration's role in introducing the curse and its price.