An ﹩r﹩-band image from Subaru of the USS 1558−003 protocluster. The large, black box shows the 6′ × 6′ field of view of MODS. The large blue circles show three overdense clumps within USS 1558−003 that were identified by Hayashi et al. (2012). The small, black circles are the HAEs from the Hayashi et al. (2016) catalog, and the small magenta ellipses are the X-ray sources from Chandra. The red rectangles mark the five galaxies with confirmed spectroscopic redshifts from our LBT observations. The two members are the ApID 10 (4C-00.62) and ApID 13.