We have investigated the most essential kaonic nucleus “K−pp” as a resonant state of the K¯NN-πΣN- πΛN coupled-channel system using a chiral SU(3)-based K¯N potential. We treat the “K−pp” resonance adequately with a fully coupled-channel complex scaling method (full ccCSM). Self-consistency needs to be considered for the energy dependence of the chiral SU(3)-based potential. In the present study, we propose a simple prescription for the treatment of self-consistency, considering the averaged threshold and averaged binding energy of mesons. With this prescription, we have successfully found the self-consistent solutions of the “K−pp” three-body resonance. The results indicate that the “K−pp” system is bound rather shallowly. In particular, when the potential parameters are constrained with the latest K¯N scattering length, the binding energy and half of the mesonic decay width are obtained as 14–50 MeV and 8–19 MeV, respectively.