Wit Studio apologizes after generative AI found in Ascendance of a Bookworm anime opening

Wit Studio Confirms Generative AI Use in Ascendance of a Bookworm

Wit Studio, the celebrated animation house behind Attack on Titan, Spy x Family, and the upcoming One Piece remake, has confirmed that generative AI was used in the opening sequence of Ascendance of a Bookworm Season 4 1

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. The admission came six days after the show premiered on April 4, following intense fan backlash on social media platforms like Twitter/X and Reddit 3

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. Eagle-eyed viewers spotted telltale distortions and irregularities in the background art that suggested AI-generated content, prompting widespread criticism of one of the anime industry's most respected studios 4

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In an official statement released on April 10, Wit Studio acknowledged the AI controversy and took full responsibility for what it described as production management shortcomings . The studio emphasized that it has "in principle, not permitted the use of generative AI in the video production of our works" and attributed the incident to failures in its inspection systems 1

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. Notably, the studio cleared NAM HAI ART, the background production company for the series, of any involvement in the matter 3

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Studio Promises to Redraw Opening Sequence

Wit Studio announced it will redraw the opening sequence entirely, with the corrected version appearing from Episode 2 onwards . The original opening has been removed from Crunchyroll's YouTube channel, and the studio confirmed that no other AI-generated content has been found elsewhere in the production 3

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. The apology extended to fans, the original author Miya Kazuki, and all related parties, with the studio pledging to revise its production process guidelines and management systems to prevent similar incidents 1

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This marks the second time Wit Studio has been caught using AI in anime production. In 2023, the studio released Dog and Boy on Netflix, which explicitly credited AI as a co-creator of AI background art and music 1

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. The experimental short listed background credits simply as "AI (+ Human)" without properly acknowledging human artists 1

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. Netflix Japan defended the decision at the time, citing support for the "labor-short anime industry," a statement that highlighted the sector's ongoing struggles with inadequate compensation for human artists 1

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Growing Concerns About AI in Anime Production

The incident reflects broader tensions within the anime industry as studios face mounting pressure to produce content at an accelerated pace. Wit Studio reportedly lost 170 million yen in the fiscal year ending May 2025, underscoring the financial strain that may drive studios toward cost-cutting measures like AI 2

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. Working conditions in the sector remain challenging, with freelance animators often receiving wages far below living standards despite the industry generating substantial revenue 1

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Other major players have also embraced AI technology. Toei Animation, the studio behind One Piece and Dragon Ball, announced a 10-year, 100 billion yen ($650 million) plan in 2025 that includes adopting next-generation technologies like AI, VR, and AR 2

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. Meanwhile, Amazon faced similar fan backlash in late 2025 after using AI-generated dubbing for shows including Banana Fish and Vinland Saga, eventually walking back the decision due to poor translation quality 2

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According to director and animator Terumi Nishii, who has worked on Jujutsu Kaisen and Death Note, several animation studios are already using AI to generate rough drafts for direction corrections, making it difficult to spot when outsourcing partners employ such tools . This revelation suggests that AI in anime production may be more widespread than publicly acknowledged, raising questions about animation quality and transparency across the industry. As production pipelines increasingly involve multiple companies across different countries, maintaining oversight becomes more complex .