We present a first-principles unification framework founded upon fundamental complex time \(\theta=\tau+it/\hbar\) defined on a Kähler manifold. From strict dimensional consistency, geometric self-consistency, and physical causality, we derive a unique master equation that unifies quantum unitary dynamics, thermodynamic irreversibility, and gravitational geometry. The coupling constant for the geometric term is uniquely fixed by the Planck length, leaving no free parameters beyond an order-one dimensionless coefficient. The framework naturally embeds quantum field theory and the full gauge structure of the Standard Model, thereby unifying all known fundamental interactions within a single holomorphic dynamical law. We analyze the physical meaning, mathematical structure, and theoretical implications of the master equation in depth, demonstrating that it constitutes a concrete candidatefor the fundamental master equation of a Theory of Everything.