The most remote isotope from the proton dripline (by 4 atomic mass units) has been observed: K31. It is unbound with respect to three-proton (3p) emission, and its decays have been detected in flight by measuring the trajectories of all decay products using microstrip detectors. The 3p emission processes have been studied by the means of angular correlations of S28+3p and the respective decay vertices. The energies of the previously unknown ground and excited states of K31 have been determined. This provides its 3p separation energy value S3p of-4.6(2) MeV. Upper half-life limits of 10 ps of the observed K31 states have been derived from distributions of the measured decay vertices.