Oshi no Ko is a dark drama anime that takes an honest look at the exploitative brutality of the entertainment industry, a narrative explored through the eyes of characters like the late Ai Hoshino, her daughter Ruby Hoshino, and the dandere Akane Kurokawa. These three girls are all fascinating and compelling characters because of this, but none of them are Best Girl. That distinction belongs to Kana Arima, who has become the fandom's favorite Oshi no Ko character by a wide margin.
Source:https://www.cbr.com/oshi-no-ko-kana-arima-popularity-explained/