Substantially optically pure (S)-trans-{4-[({2-[({1-[3,5-bis(trifluoromethyl)phenyl]ethyl}{5-[2-(methylsulfonyl)ethoxy]pyrimidin-2-yl}amino)methyl]-4-(trifluoromethyl)phenyl}(ethyl)amino)methyl]cyclohexyl}acetic acid, or a salt thereof, or a solvate thereof, which has actions of reducing amount of PCSK9 protein and increasing amount of LDL receptor.