  In a $\Lambda$CDM universe, most galaxies evolve by mergers and accretions,
leaving faint and/or diffuse structures, such as tidal streams and stellar
halos. Although these structures are a good indicator of galaxies' recent mass
assembly history, they have the disadvantage of being difficult to observe due
to their low surface brightness (LSB). To recover these LSB features by
minimizing the photometric uncertainties introduced by the optical system, we
developed a new optimized telescope named K-DRIFT pathfinder, adopting a linear
astigmatism free-three mirror system. Thanks to the off-axis design, it is
expected to avoid the loss and scattering of light on the optical path within
the telescope. To assess the performance of this prototype telescope, we
investigate the photometric depth and capability to identify LSB features. We
find that the surface brightness limit reaches down to
$\mu_{r,1\sigma}\sim28.5$ mag arcsec$^{-2}$ in
$10^{\prime\prime}\times10^{\prime\prime}$ boxes, enabling us to identify a
single stellar stream to the east of NGC 5907. We also examine the
characteristics of the point spread function (PSF) and find that the PSF wing
reaches a very low level. Still, however, some internal reflections appear
within a radius of $\sim$6 arcmin from the center of sources. Despite a
relatively small aperture (0.3 m) and short integration time (2 hr), this
result demonstrates that our telescope is highly efficient in LSB detection.
