  HO Puppis (HO Pup) was considered as a Be-star candidate based on its
gamma-Cassiopeiae-type light curve, but lacked spectroscopic confirmation.
Using distance measured from Gaia Data Release 2 and the
spectral-energy-distribution (SED) fit on broadband photometry, the Be-star
nature of HO Pup is ruled out. Furthermore, based on the 28,700 photometric
data points collected from various time-domain surveys and dedicated
intensive-monitoring observations, the light curves of HO Pup closely resemble
IW And-type stars (as pointed out in Kimura et al. 2020a), exhibiting
characteristics such as quasi-standstill phase, brightening, and dips. The
light curve of HO Pup displays various variability timescales, including
brightening cycles ranging from 23 to 61 days, variations with periods between
3.9 days and 50 minutes during the quasi-standstill phase, and a semi-regular
~14-day period for the dip events. We have also collected time-series spectra
(with various spectral resolutions), in which Balmer emission lines and other
expected spectral lines for an IW And-type star were detected (even though some
of these lines were also expected to be present for Be stars). We detect Bowen
fluorescence near the brightening phase, and that can be used to discriminate
between IW And-type stars and Be stars. Finally, despite only observing for
four nights, the polarization variation was detected, indicating that HO Pup
has significant intrinsic polarization.
