The low-surface brightness (LSB) Universe is one of the latest frontier in observational astronomy. However, uncovering the precious information contained in ultra-deep imaging is technically challenging. In this contribution, we will present one of the fundamental tools of LSB astronomers: the extended Point Spread Function (PSF). Having an extended PSF is fundamental to characterize the LSB properties of astronomical objects like the extended stellar halos, colors, structural properties, etc. In this contribution we show how to build the extended PSF (~5 arcmin in radius), at 5 bands (grizY), of one of the most important nowadays deep surveys: the Hyper-Suprime Camera (HSC) on the 8.2m Subaru telescope. These PSFs have been obtained by sampling individual point-like sources at different brightness. The techniques used here can be applied to the next generation of deep imaging astronomical surveys as the LSST.