テキストデータで学習している限界ですね。

Q. Who is the most famous Youtuber in a Sanzai category in Japan?

A. As of my training data cut-off in 2021, the most famous Youtuber in the "Sanzai" category in Japan is likely "Hikakin." Sanzai refers to beatbox in Japanese and Hikakin is a popular beatboxer and Youtuber who has gained a large following in Japan.