The low-surface-brightness (LSB; less than ~0.1% of the ground-based night sky brightness) Universe has so far been hardly explored. However, the advancement in telescope and detector technologies (e.g., ground-based Vera C. Rubin Observatory and space-based Euclid) enables in the next decade to survey the LSB Universe down to much fainter levels and over wider areas than previously possible. Coupled with deep imaging techniques and data analysis for the diffuse star light, statistical studies of galaxies and clusters of galaxies in this LSB regime promise to produce a big change in our knowledge of the hierarchical assembly of galaxies and clusters of galaxies. In this talk, I will introduce the KASI-Deep Rolling Imaging Fast optics Telescope (K-DRIFT), a linear-astigmatism-free three freeform mirror system optimized for the detection and accurate photometric studies of extended LSB features. I will also show the results with successful observations of the prototype of the K-DRIFT (K-DRIFT Pathfinder) and discuss challenges we face.