  Type II supernovae (SNe) interacting with disklike circumstellar matter (CSM)
have been suggested as an explanation of some unusual Type II SNe, e.g., the
so-called "impossible" SN, iPTF14hls. There are some radiation hydrodynamics
simulations for such SNe interacting with a CSM disk. However, such disk
interaction models so far have not included the effect of the ionization and
recombination processes in the SN ejecta, i.e., the fact that the photosphere
of Type IIP SNe between $\sim 10$-$\sim 100$ days is regulated by the hydrogen
recombination front. We calculate light curves for Type IIP SNe interacting
with a CSM disk viewed from the polar direction, and examine the effects of the
disk density and opening angle on their bolometric light curves. This work
embeds the shock interaction model of Moriya, et al. (2013) within the Type IIP
SN model of Kasen & Woosley (2009), for taking into account the effects of the
ionization and recombination in the SN ejecta. We demonstrate that such
interacting SNe show three phases with different photometric and spectroscopic
properties, following the change in the energy source: First few tens days
after explosion (Phase 1), $\sim 10 - \sim 100$ days (Phase 2) and days after
that (Phase 3). From the calculations, we conclude that such hidden CSM disk
cannot account for overluminous Type IIP SNe. We find that the luminosity ratio
between Phase 1 and Phase 2 has information on the opening angle of the CSM
disk. We thus encourage early photometric and spectroscopic observations of
interacting SNe for investigating their CSM geometry.
