  We propose a new model to generate large anisotropies in the scalar-induced
gravitational wave (SIGW) background via sound speed resonance in the
inflaton-curvaton mixed scenario. Cosmological curvature perturbations are not
only exponentially amplified at a resonant frequency, but also preserve
significant non-Gaussianity of local type described by $f_{\mathrm{nl}}$.
Besides a significant enhancement of energy-density fraction spectrum, large
anisotropies in SIGWs can be generated, because of super-horizon modulations of
the energy density due to existence of primordial non-Gaussianity. A reduced
angular power spectrum $\tilde{C}_{\ell}$ could reach an amplitude of
$[\ell(\ell+1)\tilde{C}_{\ell}]^{1/2} \sim 10^{-2}$, leading to potential
measurements via planned gravitational-wave detectors such as DECIGO. The large
anisotropies in SIGWs would serve as a powerful probe of the early universe,
shedding new light on the inflationary dynamics, primordial non-Gaussianity,
and primordial black hole dark matter.
