After decades of study of the nucleon spin structure, the deep-valence quark (high $x$) region remains difficult to access experimentally. On the other hand, the high-$x$ region is a clean testing ground of various predictions for the ratio of polarized and unpolarized structure functions, and quark polarization inside the nucleon. These predictions include relativistic constituent-quark model, perturbative QCD, holographic light-cone QCD, and Schwinger-Dyson equations. We report on a 12 GeV Jefferson Lab experiment (JLab E12-06-110) that measured the virtual photon asymmetry of the neutron, $A_1^n$. The experiment used a longitudinally polarized beam of 10.4 GeV energy and a polarized $^3$He target in Hall C. It pushed the highest $x$ value from $x=0.61$ of the 6 GeV era to $x=0.75$. Preliminary results and the current status of the analysis are presented.