Oh, yeah.. but did you notice in the CG that shu and hikarino are in the same body?? You'll notice hikarino's color palette at the left part of shu in that CG, so i strongly assume that hikarino is the one controlling most of shu's actions in his bad route and why i think he might be waiting for eki, too, since both of their kind counterparts experienced hell from bad MC (if we already played both of their bad endings). As for shu's other alters, i thought they are always together with him? But there's a possibility that they might have left shu for the time being because hikarino wanted to get rid of bad MC.
For now, our best guess is either ike or shu's other alters.