  We present GPI polarized intensity imagery of HD 100453 in Y-, J-, and K1
bands which reveals an inner gap ($9 - 18$ au), an outer disk ($18-39$ au) with
two prominent spiral arms, and two azimuthally-localized dark features also
present in SPHERE total intensity images (Wagner 2015). SED fitting further
suggests the radial gap extends to $1$ au. The narrow, wedge-like shape of the
dark features appears similar to predictions of shadows cast by a inner disk
which is misaligned with respect to the outer disk. Using the Monte Carlo
radiative transfer code HOCHUNCK3D (Whitney 2013), we construct a model of the
disk which allows us to determine its physical properties in more detail. From
the angular separation of the features we measure the difference in inclination
between the disks 45$^{\circ}$, and their major axes, PA = 140$^{\circ}$ east
of north for the outer disk and 100$^{\circ}$for the inner disk. We find an
outer disk inclination of $25 \pm 10^{\circ}$ from face-on in broad agreement
with the Wagner 2015 measurement of 34$^{\circ}$. SPHERE data in J- and H-bands
indicate a reddish disk which points to HD 100453 evolving into a young debris
disk.
