The 9mm Shigure Ui meme stems from the massive popularity of the VTuber Shigure Ui, particularly her viral music video Loli Kami Requiem. While the song is known for its catchy dance, the internet quickly latched onto the contrast between her cute character design and the menacing persona depicted in specific frames. The 9mm variant specifically highlights her holding a firearm or reacting aggressively to social media comments. It is widely used on platforms like X and Reddit to playfully threaten someone for being 'down bad' or to express a sharp, cute rejection of degenerate behavior.