Yuki Kaji’s AI software, “Soyogi Soyogi AI,” which was released a year after Attack on Titan, is set to be discontinued because of a “fundamental divergence in the ideal vision.”
Approximately a year after its July 2024 launch, Soyogi Soyogi CeVIO AI, the interactive AI software that features Yuki Kaji’s character Soyogi Soyogi, is scheduled to conclude this August, according to the Japanese news site Oricon. The app included an interactive version of Soyogi that could sing, converse with users, and even soothe them to sleep with a Kaji voice model trained by artificial intelligence. The following was the official notification regarding the app’s cancellation: “Despite the fact that many users actively appreciated the service, we regret to inform you that Soyogi Soyogi AI will be discontinued. The decision is the result of a fundamental difference in our creative team’s and the app’s operating company’s ideal vision for interacting with AI and our consumers.
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The Soyogi Soyogi AI app will be switching to the Japanese AI app “HAPPY RAT,” which provides a comparable service with animated animals, according to a recent announcement made by Yuji Kaji on his official X (previously Twitter) account. According to a formal statement posted on HAPPY RAT’s X account, “The Sooyogi AI will be deployed in a form that is approximately identical to the current Soyogi AI following the transition to HAPPY RAT. Early in the changeover, certain specifications can be different. We will progressively modify them to match the existing criteria. There was also a promotional film on X that welcomed Soyogi Soyogi to HAPPY RAT’s Happy Island, which featured a character crossover between Soyogi and HAPPY RAT.
As part of the Soyogi Fractal project, which celebrated his 20th anniversary as a voice actor, Yuki Kaji, a well-known musician and voice actor who is well recognized for his role as Eren Yeager in Attack on Titan, created Soyogi Soyogi. The CeVIO AI app, the Soyogi VoiSona software, and the special spin-off collaboration manga that Kaji and Attack on Titan creator Hajime Isayama created, The Theory of the Evil Man and AI, were among the various initiatives that were part of the project. The latter appeared in the February 2025 issue of Bessatsu Shonen Magazine.
Kaji had previously said that the Soyogi Fractal project aimed to use AI to create a welcoming environment for creatives in and out of the business. Kaji’s character, Soyogi Soyogi, was intended to be “another world of Yuki Kaji,” with characteristics and personality evolving according to the users it engaged with. Kaji had previously expressed his displeasure with AI, but he jumped ahead and developed a platform using his own AI before it was utilized against his will. He remarked, “I find it eerie, or more accurately, terrifying, that something I did not sing or discuss ends up going viral as though it had truly happened.”
August 2025 will mark the closure of Soyogi Soyogi AI. No formal date has been set for when it will switch to HAPPY RAT.