  Type II supernovae (SNe) originate from the explosion of hydrogen-rich
supergiant massive stars. Their first electromagnetic signature is the shock
breakout, a short-lived phenomenon which can last from hours to days depending
on the density at shock emergence. We present 26 rising optical light curves of
SN II candidates discovered shortly after explosion by the High cadence
Transient Survey (HiTS) and derive physical parameters based on hydrodynamical
models using a Bayesian approach. We observe a steep rise of a few days in 24
out of 26 SN II candidates, indicating the systematic detection of shock
breakouts in a dense circumstellar matter consistent with a mass loss rate
$\dot{M} > 10^{-4} M_\odot yr^{-1}$ or a dense atmosphere. This implies that
the characteristic hour timescale signature of stellar envelope SBOs may be
rare in nature and could be delayed into longer-lived circumstellar material
shock breakouts in most Type II SNe.
