We investigate the long-time asymptotics for solutions to Cauchy problem of defocusing modified Kortweg-de Vries (mKdV) equation with finite density initial data. The present paper is subsequent work our previous [arXiv:2108.03650], which gives soliton resolution mKdV in central asymptotic sector $\{(x,t): \vert \xi \vert<6\}$ $\xi:=x/t$. In paper, via Riemann-Hilbert (RH) associated problem, s...