Vivit (ビビット Bibitto) is Erich's daughter who is the Final boss of Shuusou Gyoku. Decades ago, a disastrous accident caused by cactus energy got Vivit trapped in a machine in what is called the "Other Dimension". She was eventually rescued by VIVIT.
https://en.touhouwiki.net/wiki/Vivit_(Erich%27s_Daughter)