  The GRAINE project observes cosmic gamma-rays, using a balloon-borne
emulsion-film-based telescope in the sub-GeV/GeV energy band. We reported in
our previous balloon experiment in 2018, GRAINE2018, the detection of the known
brightest source, Vela pulsar, with the highest angular resolution ever
reported in an energy range of $>$80 MeV. However, the emulsion scanning system
used in the experiment was designed to achieve a high-speed scanning, and it
was not accurate enough to ensure the optimum spacial resolution of the
emulsion film and limited the performance. Here, we report a new high-precision
scanning system that can be used to greatly improve the observation result of
GRAINE2018 and also be employed in future experiments. The system involves a
new algorithm that recognizes each silver grain on an emulsion film and is
capable of measuring tracks with a positional resolution for the passing points
of tracks of almost the same as the intrinsic resolution of nuclear emulsion
film ($\sim$70 nm). This resolution is approximately one order of magnitude
smaller than that obtained with the high-speed scanning system. With this
system, an angular resolution for gamma-rays of 0.1$^\circ$ at 1 GeV is
expected to be achieved. Furthermore, we successfully combine the new
high-precision system with the existing high-speed system, establishing the
system to make a high-speed and high-precision measurement. Employing these
systems, we reanalyze the gamma-ray events detected previously by only the
high-speed system in GRAINE2018 and obtain an about three times higher angular
resolution (0.22$^\circ$) in 500--700 MeV than the original value. The
high-resolution observation may bring new insights into the gamma-ray emission
from the Galactic center region and may realize polarization measurements of
high-energy cosmic gamma-rays.
