The following question is inspired by Bill's nice unpublished result that the dual of a non separable Banach space is decomposable. (See the previous posts Decomposable Banach SpacesDecomposable Banach Spaces, Hereditarily indecomposable Banach spaces and Separable Quotient problemHereditarily indecomposable Banach spaces and Separable Quotient problem and A question related to the separable quotient problem)A question related to the separable quotient problem.)
Definition: A dual Banach space $X^*$is is said to be $w^*$-HI if dist ($S_Y$,$S_Z$ )= 0$\operatorname{dist} (S_Y,S_Z )= 0$ for every $Y$, $Z$ infinite dimensional $w^*$ closed-closed subspaces of $X^*$. The space $X^*$ is said to be $w^*$ indecomosable-indecomposable if it is not the direct sum of two infinite dimensional w* closed$w^*$-closed subspaces.
Question I: Does there exist non separable $X$ such that $X^*$ is w*$w^*$-HI?
Question II: For $X$ HI is the second dual $X^{**}$ w*$w^*$- inecomposableinecomposable?
There exists $X$ HI such that $X^*$ is non separable and $X^{**}$= $X$ $\oplus$ $l^2(2^N)$$X^{**}= X \oplus l^2(2^N)$.