We perform numerical simulations of image defect at edges of solid images in non-contact single-component development systems using nonmagnetic toner. Line deletion at the leading edge of halftone images when the image is placed below a solid pattern often occurs in development systems in which the photoconductor drum surface and the development roller surface rotate in opposite directions in the development gap. This defect is examined by simulating development process in the region between the drum and the roller. The toner movement is traced by solving the equation of motions for toner particles. The Green function approach is used to calculate the electric field in the gap. An efficient numerical method is applied to integrate the Green function over charge distributions over the photoconductor with numerical stability.