It originally started as a throwaway joke over an illustration Ui drew of a younger version of herself, until she lost a bet against Nijisanji's Kenmochi Touya, and was forced to do a stream pretending to be a little girl on-stream using the said illustration as a static avatar on February 2020. It became a running joke on her channel from then on, ultimately debuting a Live2D model for April Fools 2020, and her occasionally doing "Loli Ui" streams with either the static or Live2D avatar, until it got a full 3D model on September 10th, 2023.
