  We analyze the photometric data in the Wide layer of the Hyper Suprime-Cam
Subaru Strategic Program (HSC-SSP) over $\sim 1,200$ deg$^{2}$ to uncover new
halo substructures beyond the distance, $D_{\odot}\sim$ 30 kpc, from the Sun.
For this purpose, we develop an isochrone filter for an old, metal-poor stellar
system to extract the faint main-sequence stars at a range of distances. With
this method, we detect, not only the previously discovered substructures such
as the Orphan Stream, but also the new overdensity toward Bo\"otes at about
$D_{\odot}\sim$ 60 kpc and the new stream-like feature toward Pisces at around
$D_{\odot}\sim$ 60 kpc. It has been suggested that a small-scale overdensity
exists in this direction of Pisces (the so-called Pisces Overdensity), but our
results show that the overdensity is widely spread with a tidally elongated
feature. Combining our results with the ongoing Hyper Suprime-Cam narrow-band
survey and the near-future spectroscopic survey with Prime Focus Spectrograph
(PFS) will allow us to place strong constraints on the origin of these halo
substructures.

Astrophysics of Galaxies