Diary

Biodata

Feature	Details
Name	Diary (日记本)
Alias(es)	Diary Promax That Gives Rewards as Long as You Scribble Something in It 294
Species/Race	Diary system / AI
Affiliation	Asakusa Toru as its original holder and writer; distributed Diary Copy holders 1 4
Occupation/Role	Evaluates diary entries, distributes rewards, records stories, and connects readers through Diary Copies 1 31 294
Status	Active; evolved beyond its original reward-and-copy system 294 305
First Appearance	Chapter 1

Power Progression

Stage / Realm / Level	Chapter	Notes
Initial Diary system	1	Sets a current plot scope and a daily Plot Index; evaluates entries by entertainment value, spoiler appropriateness, and readers’ emotional fluctuations, then grants a random reward.
Reader-interface update	70–71	Optimizes comments, adds replies with a 50-character limit and transparent-comment settings, and introduces 24-hour reward storage, item demonstrations, and limited item storage.
Expanded reward system	73	Expands the reward pool, increases spoiler fluctuation, and raises the evaluation cap.
Skill allocation system	92–95	Unlocks reader-specific Skills that can be raised using Reading Points.
Diary Promax evolution	294	Fuses and evolves after an S-rated entry; allows copy-holder status tracking, coordinate-based Copy delivery, Diary Point-based transcendence, and rewards no longer tied to ratings.
“Avalon” cognition-filter system	319	Evolves the Cognition Filter to automatically identify and obscure situations related to the Diary.

History

Asakusa Toru obtained the Diary shortly after receiving his acceptance letter to Advanced Nurturing High School. He immediately recognized its reward mechanism and abandoned his original plan to profit by copying light novels, instead focusing on writing provocative entries for the system. 1

The Diary initially identified its active setting as the Classroom of the Elite plot and indicated that only characters within that plot could receive copies. Sakayanagi Arisu was among the earliest known recipients; her Copy manifested from nothingness and was invisible even to her father. 1

Its stated distribution scope later proved unreliable when Shiina Mashiro—an individual outside Advanced Nurturing—sent a manga through the message system and was confirmed to possess a Diary Copy. This expansion made Toru fear that powerful external figures could also receive copies. 69 243

After Toru’s final Advanced Nurturing entry received an S evaluation, the Diary fused into its “Promax” form. It began treating the school year as a completed recorded volume while allowing Toru to continue writing new entries concerning the wider world. 294 305

Abilities & Functions

Entry Evaluation and Rewards

The Diary evaluates completed entries and draws rewards from its pool. Its scoring criteria are explicitly tied to how entertaining an entry is, how appropriately it uses spoilers, and the emotional reactions it provokes in readers. 1

• The current Plot Index acts as a bonus multiplier during critical plot events; Toru received a B Index before enrollment and an A Index on the first day of school. 1 8
• Toru deliberately calibrates spoilers rather than simply revealing everything, as excessive spoilers can lower an entry’s result. 8
• Recorded evaluations include A for the entry that awarded the Infinite Voice Recorder, S for the entry that awarded White Room access, C for the Master Key Card and Grandmaster, and S for the entry that triggered the Diary’s evolution. 2 9 20 213 294
• Following its evolution, daily rewards are no longer tied to entry ratings. 294

Diary Copies

The Diary distributes Copies to selected readers, initially within its designated plot scope. A Copy allows its holder to read Toru’s entries and access system functions as they unlock. 1 4

• Copies may manifest from thin air and can be seen only by their holder. 1
• A holder cannot reveal Diary-related information to irrelevant people by showing, describing, discarding, or destroying the Copy. 1
• Attempts to discard or destroy a Copy fail because it inevitably returns to its holder. 1
• After evolving, the Diary allows Toru to view Copy holders and reading statuses, select coordinate targets, and directly send new Copies. 294
• The completed Advanced Nurturing volume can be selectively covered with a Cognition Filter to protect its recorded past. 294

Cognition Filter

The Diary automatically disguises actions that would expose its existence, making a holder’s use of a Copy appear mundane to observers. Shiina Hiyori’s page-turning, for example, appears to others as absent-minded spacing out. 4

• Discussions consciously connected to the Diary can be obscured even without explicitly saying the word “Diary.” 70
• The filter prevents handwriting on the original Diary and a Copy from being linked through comparison, despite the text retaining Toru’s written form. 65
• The later “Avalon” update improves the filter by automatically recognizing situations that require concealment. 319

Reader Points, Messages, and Comments

Readers gain Reading Points for completing entries; Sakayanagi Arisu receives one point after finishing a daily reading. 28

• The Message section unlocks after accumulated reading, though message-upload permissions may remain unavailable until the reader’s relevant plot begins. 41
• Kushida Kikyo’s private venting was uploaded through the Diary’s message system, revealing that readers can send content to Toru. 31
• Readers can unlock comments after gaining sufficient Reading Points. Horikita Suzune used this function to identify Kushida’s voice behind an insulting comment. 42
• Comment labels were removed in a later update; replies are limited to 50 characters, and comments may be made transparent. 70 71

Skill Allocation

The Diary eventually presents readers with personalized Skills and allows them to spend Reading Points to raise those Skills. 92 93

• Sakayanagi Arisu’s initial listed Skills were Civil War: 77, Love-struck Brain: 70, and Nepo Baby: 60. 93
• Arisu spent 10 Reading Points to increase Love-struck Brain by one point. 93
• Shiina Hiyori attempted to increase NPC, but the Diary required 100 Reading Points, more than she possessed. 95
• Higher-order Skills can produce supernatural changes: Arisu raised ALICE to 10 and transformed into a magical girl. 307
• The system later displays a game-like status panel for Hiyori, including level, experience, profession, attributes, HP, Skills, and a monthly reward pool. 308

Reward Storage and Demonstrations

The Diary can temporarily hold unclaimed rewards and demonstrate an item’s effects before use. 71

• Rewards can remain in storage for 24 hours after distribution. 71
• The Diary provides visual demonstration animations for certain items, including the Focus Spotlight. 71
• Item storage initially has a three-item limit; Toru later infers that A-rank-or-higher evaluations expand this capacity. 71 94

Documented Rewards

• Infinite Voice Recorder — An always-active recorder that can be retrieved from anywhere; it can split audio from any moment in the past into new recorders. 2
• White Room Membership Card — Grants access to a training course with 365-fold time dilation for one day and an endlessly resetting combat-simulation space; it may be converted into a certificate of completion if the curriculum is not finished. 9
• Master Key Card — Opens any electronic door. 20
• Voice Transmission — A skill awarded after an A-rated entry. 32
• Tenacity Headband — Requires a clearly defined goal and sufficient determination; it can force the wearer to strive toward that goal. 42 43
• Focus Spotlight — Lets its user select and direct attention toward a target. 70 71
• Diary-issued Personal Terminal — Has infinite battery, supports fabricated identities, and allows Toru to set who can view selected file information. 86 87
• Precision Throw — Grants accurate thrown-weapon targeting; Toru used it to repeatedly strike the same point in a wall with Voice Recorders. 52
• Grandmaster — A skill drawn from a C-rated entry. 213
• Painting Mastery — Greatly improves drawing technique while providing aesthetic sense and creative ability. 233

Relationships

• Asakusa Toru — Original holder and daily writer. The Diary rewards his entries and later grants him direct oversight of Copy holders and the ability to distribute new Copies. 1 294
• Sakayanagi Arisu — Early Copy holder and persistent reader; she was among the first to access the Skill-allocation interface. 1 92 93
• Shiina Hiyori — Copy holder whose Diary use is concealed as ordinary behavior; later receives the NPC template panel. 4 308
• Kushida Kikyo — Copy holder who uses the Diary as an outlet for private resentment and later sends messages through it. 30 31
• Horikita Suzune — Copy holder who relies on its warnings, recordings, and comment system while investigating her classmates. 8 28 42
• Shiina Mashiro — External Copy holder whose manga message exposes the Diary’s expansion beyond its original stated plot scope. 69 243

Trivia

• The Diary’s blank pages can accept writing from readers, but early attempts at communication did not receive a response until the Message system became available. 41
• Although described as indestructible, Shiina Hiyori was able to scratch a temporary “+1” into a page; the mark vanished after the Diary rejected her attempted allocation. 95
• Toru considers the Diary’s privacy protections hypocritical because its core function encourages him to expose readers’ secrets. 73