We investigate localization transitions in a one-dimensional non-Hermitian quasiperiodic chain with period-2 mosaic modulation and nonreciprocal hopping. We show that tuning the degree of non-Hermiticity can induce a rich reentrant localization behavior: As the hopping asymmetry increases, reentrant localization successively emerges, disappears, resurges, and ultimately vanishes. By mapping the non-Hermitian Hamiltonian to a Hermitian reference chain via an imaginary gauge transformation and performing a transfer-matrix analysis, we introduce an effective Lyapunov exponent ${\gamma }_{\mathrm{eff}}={\gamma }_{\mathrm{qp}}-\alpha$, where ${\gamma }_{\mathrm{qp}}$ denotes the Lyapunov exponent of the Hermitian chain and $\alpha$ characterizes the hopping asymmetry. The interplay between ${\gamma }_{\mathrm{qp}}$ and $\alpha$ reveals that reentrant localization and its resurgence arise from the competition between quasiperiodic disorder and non-Hermiticity. Numerical analyses of participation ratios, single-particle spectra, and spectral winding numbers corroborate these findings.

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• Anderson localization
• Disordered systems
• Quasicrystals
• Tight-binding model