《死神公主與異書館之怪》延續《說謊姬與盲眼王子》與《邪惡國王與出色勇者》等「繪本系列」的黑暗童話美學，維持標誌性的手繪畫風與文學式敘事，同時在視覺與玩法上進行大幅進化。本作的世界被塑造成壓抑而詭異的黑白手繪景色，玩家將直接干涉這些彷彿活著的繪本頁面，透過撕裂、翻動與破壞來推動故事，使探索本身成為一種「介入童話世界」的體驗。

作品的核心圍繞在名為「死神病」的恐怖流行病，它會逐漸奪走患者原本的形體，使人變成繪本中的角色，最終蛻變成怪物。少女莫諾的姐姐正是罹患死神病後被送入隔離地「異書館」的受害者之一。為了找回姐姐的下落，莫諾踏入這座被遺忘與封印的巨大收容所，面對其中盤踞的怪物與崩壞的少女靈魂。她與山羊形怪物「梅爾亨迪亞」訂下契約，進入那些由創傷具象化的異質繪本世界，在每一本書中直面少女們因恐懼、後悔或罪惡所形成的悲痛景象。

莫諾的成長同樣是故事的一部分。她出身歌劇名門，卻因天賦不足而長期遭到父母冷漠，獨自住在劇院的閣樓度過孤獨的童年。唯一照亮她世界的人，是才華洋溢的姐姐安雪兒。然而，安雪兒在感染死神病後被送往異書館，自此音訊全無。得知真相的莫諾無法接受姐姐最終變為怪物的命運，只能獨自前往異書館尋求解救方法。她與梅爾的契約建立在不得不的共生關係之上，雖然梅爾厭惡人類、把莫諾視為利用工具，但兩人在旅程中逐漸形成微妙的羈絆。隨著莫諾逐步深入繪本世界，她也看清每位少女身上的創傷如何扭曲周遭景色與怪物型態，而所謂的「死神姬」正是這些極限情感的具象化。要拯救她們，必須直視這些被黑白陰影吞噬的心靈深處。

玩法方面，呈現出獨特的「可操作繪本」體驗，探索與謎題構成遊戲主體，而真正的亮點是玩家能直接操控怪物梅爾，以他的「紙喰」能力吞噬並破壞世界中的黑白元素。無論是岩石、樹木、牆壁還是怪異塗鴉，只要是死神病形成的紙之世界，都能被梅爾一口撕裂。隨著吞噬量提升，他會逐漸變得巨大且強力，但若吸收過度則會陷入暴走，導致失去控制，使莫諾陷入危險。因此，需要在讓梅爾強化與避免他失控之間維持微妙平衡。

與破壞相對應的，是莫諾擁有的翻頁能力。她能操作世界中仍保有色彩的部分，像翻動書頁般掀起場景，揭露隱藏的道路、機關或秘密區域。破壞與翻頁兩種操作相互補足，使玩家可靈活拆解地圖與謎題，面對愈加複雜的關卡配置。每本繪本世界的最深處都存在著徹底變異的少女，她們的外形、語調與攻擊方式皆由自身恐懼所塑造。擊敗她們後，黑白壓抑的世界會瞬間恢復色彩，象徵少女得以從痛苦中解放。

遊戲的畫面風格也展現出極高辨識度。整個世界以純黑白筆觸構成，營造出壓抑、孤獨且病態的氛圍。扭曲的樹木像伸展的肢體、建築充滿陰影與裂紋，而少女創傷則化為怪物與扭曲空間。當救贖發生，黑白世界瞬間轉為溫柔而暖色的景象，視覺上的強烈對比更突顯故事的情感重量。

自情報公開以來，本作便在日本與亞洲地區受到高度關注。《說謊姬與盲眼王子》與《邪惡國王與出色勇者》因獨特畫風與動人敘事而備受好評，因此玩家普遍期待本作能成為系列精神的更成熟延伸。黑白手繪的藝術風格引起大量討論，許多人認為其氛圍營造遠比過往作品更有張力。此外，「紙喰」與「翻頁」所構成的全新玩法，也被認為是系列中最具互動感的一次嘗試。雖然目前仍未正式發售，但多數玩家普遍抱持正面期待，希望本作能呈現更深刻的黑暗童話敘事。

The Princess of Death and the Monster of the Forbidden Library continues the dark-fairy-tale aesthetic established by The Liar Princess and the Blind Prince and The Wicked King and the Noble Hero, carrying forward the series’ signature hand-drawn art style and literary narrative voice while significantly evolving its visuals and gameplay. The entire world is rendered in an oppressive, uncanny black-and-white illustration style. Players directly interact with these seemingly living picture-book pages—tearing, turning, and breaking them apart—to drive the story forward, turning exploration itself into a form of “intervening in a twisted storybook world.”

At the center of the narrative is the terrifying epidemic known as the “Reaper’s Disease.” It gradually strips patients of their human form, turning them into characters trapped within picture books, and eventually transforming them into monsters. Mono’s older sister is one such victim—taken away to the quarantine facility known as the Forbidden Library after becoming infected. To uncover what happened to her sister, Mono ventures into this massive, abandoned, sealed-off institution, now overrun by monsters and the shattered souls of afflicted girls. She forms a reluctant pact with a goat-like creature named Maerhendia, entering picture-book worlds shaped by trauma and confronting scenes born from fear, guilt, regret, and obsession.

Mono’s own growth is deeply interwoven with the story. Born into a renowned opera family, she spent her childhood neglected by her parents due to her lack of talent, living alone in the attic of the theater. The only person who ever shone light into her life was her gifted and beloved sister, Ancher. But when Ancher contracted the Reaper’s Disease and was taken to the Forbidden Library, all contact was lost. Upon learning the truth, Mono refuses to accept that her sister is destined to become a monster, and sets out alone to find a way to save her. Her pact with Maer is one born of necessity; Maer despises humans and treats Mono merely as a tool, yet over the course of their journey a subtle, dangerous bond begins to form. As Mono delves deeper into each picture-book realm, she witnesses how each girl’s trauma twists landscapes and shapes monstrous forms. The so-called “Princess of Death” is the ultimate embodiment of these extreme emotions. To save others, Mono must confront the darkness consuming their hearts.

In terms of gameplay, the title offers a distinctive “playable picture-book” experience focused on exploration and puzzle-solving, with its standout feature being the ability to directly control Maer and use his “Paper-Devour” ability to consume and destroy black-and-white elements in the world. Whether it is rocks, trees, walls, or eerie scribbles—anything formed from the paper-world created by the Reaper’s Disease can be torn apart. As Maer devours more, he grows larger and more powerful, but overeating triggers uncontrollable rampages that endanger Mono. Players must maintain a delicate balance between empowering Maer and preventing him from losing control.

Complementing destruction is Mono’s page-turning ability. She can manipulate the remaining colored portions of the world, peeling back parts of the environment like turning the pages of a book, revealing hidden paths, mechanisms, or secret spaces. The interplay between tearing and page-turning creates layered puzzle-solving and allows for increasingly complex stage designs. At the deepest part of each picture-book realm awaits a fully corrupted girl whose appearance, voice, and attacks manifest her deepest fears. Defeating her restores color to the oppressive monochrome world, symbolizing her release from suffering.

The visual presentation is one of the game’s strongest defining traits. The world’s pure black-and-white hand-drawn style creates an oppressive, lonely, and unsettling atmosphere. Trees contort like strained limbs, buildings cast sickly shadows, and each girl’s trauma materializes as bizarre creatures and warped spaces. When salvation occurs, the abrupt return of soft, warm colors contrasts sharply with the monochrome gloom, emphasizing the emotional weight of each story.

Since the game’s initial reveal, it has attracted significant attention across Japan and Asia. The previous picture-book titles were praised for their unique art and tragic beauty, leading many fans to view this new entry as a more mature evolution of the series’ spirit. Its bold black-and-white art direction has become a major talking point, with players noting its strong emotional impact and artistic presence. Additionally, the combination of the Paper-Devour and page-turning systems is seen as the most interactive and gameplay-focused approach the series has attempted to date. Although the game has yet to be released, overall player sentiment remains highly positive, with many hoping it will deliver an even deeper and more resonant dark-fairy-tale experience.