We present a new study of the τ−→h−h−h+ντ decays at Belle. Previous measurements of the branching fractions of these decays at Belle and BABAR showed significant difference, especially for the τ−→K−K+K−ντ mode. The dominant systematic uncertainty is related to the K/π identification (PID). There are two sources of the PID uncertainty: insufficient accuracy of the experimental misidentification efficiency correction for the low momentum pions from τ decays and impact of the additional γ-s on the identification. To improve the accuracy of the misidentification efficiency correction we utilize KS 0(→π+π−) sample. Additional γ-s in the vicinity of the track give notable impact on the PID, hence we apply special γ-veto. The systematic uncertainties are monitored by specially constructed estimator.