We are developing the GRAINE project, which consists of a 10 MeV–100GeV cosmic
$\gamma$
-ray observation with a precise (0.08
$^\circ$
at 1–2GeV) and polarization-sensitive (50% or below the minimum ...detectable polarization for the Vela pulsar above 100 MeV) large-aperture-area (
$\sim$
10m
$^2$
) emulsion telescope, by repetitive long duration balloon flights. In 2015, we performed a Japan–Australia JAXA collaborative balloon experiment at the Alice Springs balloon-launching station. The telescope had a 3780cm
$^2$
aperture and was aloft for a total of 14.4h. The experiment aims to detect the well-known bright Vela pulsar
$\gamma$
-ray source and thereby demonstrate the overall performance of the emulsion
$\gamma$
-ray telescope. The design, improvements, and preparations as well as the 2015 balloon experiment are described in this paper. Analysis of the data from this experiment is ongoing.
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