Clearly, it is non-Hermitian. This non-Hermitian framework is regulated [20] by the physical constraints, assuming the
initial and final conditions of relaxation properties and thermal state conditions. In the present study, we have reinterpreted
this framework by reducing the thermal disturbance applied to the thermal state. This study yields the equivalence of the
following two pictures, namely such a spin system with a random field due to a heat bath as is defined in a Hilbert space
and a finite-size system with effective interactions defined in a double Hilbert space. The correspondence of these two
systems yields such perspective that the thermal disturbance is described by the effective non-Hermitian interactions. The
alternative relation between the original and TFD spaces is clarified as shown