The present patent application has for an object an agent for the simultaneous brightening and coloring of keratin fibers based on a coupler-developer combination that has a basic pH and contains as developer at least one heterocyclic hydrazone derivative of formula (I) or a physiologically compatible salt thereof, at least one common coupler and as oxidant at least one combination of persulfate salts and hydrogen peroxide or an addition compound thereof; a multicomponent kit and a method for coloring keratin fibers. ##STR00001##