  We present a pilot study to assess the potential of Hyper Suprime-Cam Public
Data Release 2 (HSC-PDR2) images for the analysis of extended faint structures
within groups of galaxies. We examine the intra-group light (IGL) of the group
400138 ($M_{\rm{dyn}}= 1.3 \pm 0.5 \times 10^{13} $M$_{\odot}$, $z\sim 0.2$)
from the Galaxy And Mass Assembly (GAMA) survey using Hyper-Suprime Cam Subaru
Strategic Program Public Data Release 2 (HSC-PDR2) images in $g$, $r$, and $i$
bands. We present the most extended IGL measurement to date, reaching down to
$\mu_{g}^{\rm{lim}}=30.76$ mag arcsec$^{-2}$ ($3 \sigma$; $10 \times 10$
arcsec$^{2}$) at a semi-major axis of 275 kpc. The IGL shows mean colour values
of $g-i=0.92$, $g-r=0.60$, and $r-i=0.32$ ($\pm$0.01). The IGL stellar
populations are younger ($2-2.5$ Gyr) and less metal-rich ([Fe/H] $ \sim -$0.4)
than those of the host group galaxies. We find a range of IGL fractions as a
function of total group luminosity of $\sim 2-36 \%$ depending on the
definition of IGL, with larger fractions the bluer the observation wavelength.
The early-type to late-type galaxy ratio suggests that 400138 is a more evolved
group, dominated by ETGs, and the IGL fraction agrees with that of other
similarly evolved groups. These results are consistent with tidal stripping of
the outer parts of Milky Way-like galaxies as the main driver of the IGL
build-up. This is supported by the detection of substructure in the IGL towards
the galaxy member 1660615 suggesting a recent interaction ($<1$ Gyr ago) of
that galaxy with the core of the group.
