Wit Studio, the legendary Japanese animation house behind the likes of Attack on Titan, Spy x Family, and Vinland Saga, has confirmed in an official statement that “generative AI was utilized in the production process” of its latest project, Ascendance of a Bookworm. The announcement comes less than a week after the first episode of the anime’s fourth season aired on April 4, which prompted questions from fans regarding the background art in Ascendance of a Bookworm’s opening song.
“Regarding our anime production, ‘Ascendance of a Bookworm: The Lord’s Adopted Daughter’ (hereinafter referred to as “this work”), we conducted an investigation into the production process of this work, including the opening sequence, based on the feedback we received after April 4, 2026,” reads the statement on Wit Studio’s official website, per Google’s machine translation from the original Japanese). “As a result, we confirmed that [genAI] was used in the production process of some cuts in the opening sequence.”
AI generated backgrounds in the opening of the new Ascendance of a Bookworm season. Very unfortunate. https://t.co/rbjknegFhr pic.twitter.com/V9CD6KIiMM
— ukloim (@ukloim) April 4, 2026
The opening song in question has been removed from Crunchyroll’s YouTube channel, and Wit Studio notes in its statement that “the opening sequence will be replaced with the completed version using the aforementioned background art materials” for all future episodes of Ascendance of a Bookworm.
The anime is an adaptation of a light novel series that debuted back in 2013 about a librarian who’s crushed to death by books and becomes reincarnated as a small child in a world where books are scarce and reserved for aristocrats. The anime series began in 2019 and Wit Studio didn’t take over production until the fourth season which first started airing earlier this month.
“While we at our company are always interested in and closely monitor new technologies related to video production, we have, in principle [. . .] not permitted the use of generative AI in the video production of our works, including this one,” continued the statement. “Despite this, the current situation has occurred solely due to shortcomings in our production management and inspection systems, and we take full responsibility for this series of events. As the production company of this work, we sincerely apologize to our fans, the original author, and all other related parties.”
While Wit Studio made a point of noting that NAM HAI ART, the production studio in charge of the background art for Ascendance of a Bookworm, is not to blame for the oversight, it does lend additional credence to a statement made by director and animator Terumi Nishii, who has worked on the likes of Jujutsu Kaisen and Death Note, earlier this year. According to Nishii’s post on Bluesky, several animation studios are already “using AI to generate rough drafts for direction corrections,” which makes it difficult to spot when scenes are outsourced to other production companies.