Shizuku AI, a startup founded by Akio Kodaira (X username: @cumulo_autumn), has completed its seed funding round. Andreessen Horowitz (a16z), which led the round, announced the investment on February 9. The amount raised was not disclosed.
Shizuku AI has introduced an AI VTuber named “Shizuku,” which is capable of conversing with viewers on YouTube.
What Is a VTuber?
VTuber is short for Virtual YouTuber and refers to a form of video content in which a two-dimensional or three-dimensional avatar, rather than a real person, appears on screen to deliver videos or live streams. Traditionally, VTubers have been operated by humans—such as content creators or voice actors—who effectively function as the performers behind the scenes. The concept of VTubers became firmly established after the emergence of KizunaAI in 2016.
Shizuku, by contrast, is an AI-driven VTuber. As a result, responses to viewers’ comments are generated automatically.
According to a16z, Shizuku opened its YouTube account in January 2023. In January of this year, it released Version 2.0. Shizuku 2.0 credits Mana Kanaka as its voice provider. Kanaka is also the voice provider for the speech model “MANA,” and Shizuku is believed to operate by recording real human voice data and using it as a foundation from which AI generates new spoken output.
The developer and founder and CEO of Shizuku AI, Akio Kodaira, completed a master’s degree in mechanical engineering at the Tokyo Institute of Technology (now the Institute of Science Tokyo) in 2018. In August 2025, he obtained a Ph.D. in Mechanical Engineering from the University of California, Berkeley.
According to reporting by Nikkei on the seed funding, Shizuku AI was founded in San Francisco in August 2025, around the same time that Kodaira earned his doctoral degree.
a16z’s First Investment in a Japanese Startup
As noted above, the amount raised in the seed round has not been disclosed. However, according to the Nikkei report cited earlier, the company’s valuation was set at $75 million.
While the specific use of funds has not been clearly disclosed, an a16z press release states:
“If you’re passionate about AI companions, character design, or the intersection of technology and entertainment, Shizuku AI is hiring in Japan and beyond,”
suggesting that talent acquisition is expected to be one of the intended uses of the capital.
For a16z, the investment in Shizuku AI marks its first investment in a Japanese startup. In its press release, the firm commented as follows:
“We’re thrilled to lead Shizuku AI’s seed round. In the coming age of AI agents, we believe theirs will be the ones people genuinely want in their lives. Akio has been working toward this future longer than almost anyone, and we couldn’t be more excited to help him realize it.”
