High-cadence ultraviolet, optical, and near-infrared photometric and low-resolution spectroscopic observations of the peculiar Type II supernova (SN) 2018hna are presented. The early-phase multiband light curves (LCs) exhibit the adiabatic cooling envelope emission following the shock breakout up to ~14 days from the explosion. SN 2018hna has a rise time of ~88 days in the V band, similar to SN 1987A. A ^56^Ni mass of ~0.087+/-0.004M_{sun}_ is inferred for SN 2018hna from its bolometric LC. Hydrodynamical modeling of the cooling phase suggests a progenitor with a radius ~50R_{sun}_, a mass of ~14-20M_{sun}_, and an explosion energy of ~1.7-2.9x10^51^erg. The smaller inferred radius of the progenitor than a standard red supergiant is indicative of a blue supergiant progenitor of SN 2018hna. A subsolar metallicity (~0.3Z_{sun}_) is inferred for the host galaxy UGC 07534, concurrent with the low-metallicity environments of 1987A-like events.