Denwa Nikki

Lore & Background

The twelve Future Diaries are not generic omniscience engines. Each one is a narrow lens focused on a single domain of human experience—snowfall, video footage, game scores, phone calls—and the holder must interpret the data within that narrow frame. The Phone Diary, in particular, is deceptively simple in concept but devastating in application. A single intercepted conversation can reveal a meeting time, a hidden location, a betrayal whispered between two rivals. In a game where the participants are sealed inside a closed world and cut off from the outside, a phone call becomes one of the few remaining channels of information, and the one who can read every call holds a quiet, constant advantage.

The diary's power is bounded by its medium: it only surfaces information that passes through a telephone. It cannot read a face-to-face conversation, a text message, or a radio broadcast. This limitation forces the holder to think strategically about when and where phone calls will occur, and to position themselves to exploit the data the diary surfaces. In the hands of a careful player, the Phone Diary becomes a surveillance network; in the hands of a careless one, it is merely a notepad that records who called Mom.

Within the Deity Selection Game's rules, the Phone Diary is no more or less powerful than the other eleven. There is no hierarchy among the diaries—only the holder's ingenuity determines how lethal the information proves. The game's designer, the Deity, ensured that no single diary grants an unassailable edge, and the Phone Diary's narrow focus is part of that balance. Its value rises and falls with the holder's ability to act on what they overhear before the conversation's participants realize they have been read.

In Their Own Story

The hallway outside the apartment was quiet, the kind of silence that pressed against the eardrums. She sat on the edge of the bed, the Phone Diary open on her lap, its pages still blank. Down the hall, two floors below, a phone was ringing. She could hear it—a thin, tinny trill bleeding up through the floorboards. The diary's pages fluttered, ink bleeding into the paper like watercolor in rain. A name. A number. And then, in a slanting scrawl, the words: *'…meet me at the old station. Bring the key. Tell no one.'* She closed the diary. The ringing stopped. In the silence that followed, she smiled, and the smile did not reach her eyes.

Reader's Guide

The Deity Selection Game operates under a fixed rule-set established by the current Deity before the contest begins. All twelve diary holders are sealed within a closed world; no external information, supply, or person may enter or leave the arena for the duration of the game. This 'no outside interference' clause is absolute: even if a holder somehow contacts the outside, the information or aid cannot cross the boundary.

Each diary is bound to its holder. If a holder dies by any means—killed by another participant, an accident, or the Deity's direct intervention—their diary is destroyed and that participant is eliminated from the contest. The diary cannot be transferred, copied, or used by a second person. Inheritance of the Deity's power occurs only upon the game's conclusion: the last surviving holder assumes the role of Deity, gaining the authority to design the next cycle's rules and select the next set of twelve participants.

The game operates under a time limit set by the Deity. If the timer expires and more than one participant remains, the Deity may intervene directly to force a resolution, though the exact mechanism of this intervention is left to the Deity's discretion in each cycle.

Edge cases the audience infers: a diary that depends on an external system (such as the Phone Diary, which requires an active call) is rendered inert if its source is unavailable. The holder is not protected by the diary's existence—possession grants knowledge, not physical invulnerability. A holder who is unconscious or separated from their diary simply loses access to its information until they recover it, but the diary itself persists and re-binds upon reunion.

Did You Know?

• Each of the twelve Future Diaries is deliberately narrow in scope; the Phone Diary only surfaces telephone data and cannot intercept in-person conversations, texts, or broadcasts, making its utility highly situational.
• The Deity Selection Game is designed so that no single diary holds an inherent power advantage over the others—the twelve are balanced by their differing domains rather than by strength tiers.
• The closed-world rule means participants cannot simply call for police, family, or outside help; the Phone Diary's information is only as useful as the holder's ability to act on it within the sealed arena.
• The diary's data is passive: it records and displays what is spoken on a call, but it does not allow the holder to place calls, block numbers, or alter the conversation in any way.