We report on the discovery and evolution of a Type IIP supernova (SN), KSP-SN-2016kf, observed by KMTNet Supernova Program in the outskirts of a small irregular galaxy within a day after the explosion. We present multi-wavelength $BVI$ photometry and the spectroscopy of the SN and its host galaxy. The light curve of KSP-SN-2016kf is relatively luminous, reaching peak absolute magnitude of $M_V=-17.6$ which is followed by a flat plateau with $V$-band decay slope of $0.53$ mag per 100 days -- a slow rate according to the peak absolute magnitude and decay rate correlation. KSP-SN-2016kf has unusually luminous radioactive tail at $M_V=-15.4$ which means $\sim$0.14 $M_\Sun$ of $^{56}$Ni is required to power the late light curve that is among the highest $^{56}$Ni mass observed for Type IIP SN. In addition, this SN has a \emph{very} long rise time (i.e., $t_\text{rise,V}=19.9\text{d}$  and $t_\text{rise,I}=50.0\text{d}$), giving evidence for a large progenitor star. In order to find the best fitting progenitor and explosion energy, we construct a grid of radiation transfer hydrodynamic SN simulations in various population synthesis progenitor models and find that the light curves are best fitted by a model with zero-age main sequence mass $M_\text{ZAMS}=14.6M_\Sun$, progenitor radius $R=824 R_\Sun$, and explosion energy 1.36 foe. Finally, we comment on the possibility of ejecta--Circumstellar material (CSM) interaction.