This paper investigates a class of output -mask -based adaptive neural network (NN) tracking control for nonlinear stochastic time -delayed multi -agent systems (STMASs) based on a unified event -triggered approach. The output signal relies on an output mapping acted as a mask, defined as a privacy -protection -like method, so that the internal state of one agent cannot be identified by other distrustful eavesdroppers or attackers. Moreover, the construction of a unified event -triggered control scheme retains the advantages of the saturation threshold triggering strategy, incorporates distributed errors, and increases the flexibility of thresholds. Furthermore, for stochastic time -delay multi -agent systems, the initial value limitation of the conventional first -order filter is removed by a first -order Levant differentiator, and a new estimation term in the fuzzy observer is established to solve the nonlinear fault. The unknown function in purefeedback form is addressed via combining Butterworth low-pass filter and radial basis function neural networks (RBF NNs). Finally, the boundedness of all signals in the closed -loop systems is demonstrated, and the effectiveness of the proposed algorithm is verified by some simulation results.