Wit Studio Used AI Despite Its Own Ban, Will Redraw Opening

Wit Studio, the Japanese animation house behind Attack on Titan, Spy x Family, and Vinland Saga, has confirmed that generative AI was used in the opening sequence of Ascendance of a Bookworm Season 4. That would be notable on its own. The part that makes it genuinely damning is that Wit Studio has a policy explicitly banning it.

Season 4 of the isekai series aired its first episode on April 4, and viewers flagged the opening almost immediately. A post on X called out what appeared to be AI-generated backgrounds in the opening song, with comparison images circulating alongside it. Wit Studio launched an internal investigation and, less than a week later, published an official statement on its website confirming the findings. Per a machine translation of the original Japanese, the studio stated: "we confirmed that [genAI] was used in the production process of some cuts in the opening sequence."

The studio was clear about where it stands on this. "In principle, we have not permitted the use of generative AI in anime production in our works," the statement reads, with the sole documented exception being The Dog & The Boy, a short film produced in 2023 as a deliberate technological experiment. That was a conscious, disclosed choice. This was not.

How It Happened, and Who Takes the Hit

Wit Studio was careful to note that Nam Hai Art, the company responsible for the background art on the opening, bears no blame for the incident. The studio took full responsibility, pointing to failures in its own production management and quality control systems. That framing matters. It isn't a deflection onto a subcontractor; it's an acknowledgement that Wit's own oversight mechanisms failed to catch something its policy was supposed to prevent.

That context connects directly to something director and animator Terumi Nishii flagged earlier this year. In a post on Bluesky, Nishii noted that animation studios are already using AI to generate rough drafts for direction corrections, and that this makes it significantly harder to identify AI usage when work is outsourced to other companies. Modern anime production is deeply fragmented, with different studios handling different elements across different countries. Wit's policy existed. Its systems for enforcing that policy across an entire production pipeline, apparently, did not.

The practical outcome: the opening sequence has been pulled from Crunchyroll's YouTube channel, and Wit has confirmed the redrawn version will replace it from Episode 2 onwards. The studio also says its investigation found no other instances of AI use in the rest of the season.

Credit where it's due, Wit moved quickly here. The episode aired April 4, fans raised concerns, and a full statement with a concrete remediation plan followed within days. That's not the behaviour of a studio trying to quietly bury something. But the speed of the response doesn't change what the situation reveals: a studio with a written anti-AI policy shipped AI-generated content anyway, because the internal checks weren't there to stop it. Having a policy and having the infrastructure to enforce it are two different things, and right now Wit only has one of them. Whether the guideline revisions the studio promises will actually close that gap is the question every anime fan watching this story should be asking.

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