When this building was finished, it functioned as an annex for the neighboring HHStyle flagship store, designed by SANAA. That's how it got its name. In January 2008 however, HHStyle have left their casa and since then new tenants have arrived in the black bunker. It looks like a bunker, but folded in origami-style. It's an angular black construction made out of 16 mm steel plates that's as startling as some of the area's high-fashion apparel. It is painted with a zinc-based primer fluoropolymer paint. The lease for the site covered two areas, one for a ten-year period, and one for half that duration. The architect thus was called upon to concentrate most of the building on the ten-year plot, leaving a fair part of the site empty. The building consists of 2 stories plus a basement. New buildings in Tokyo are not allowed to block more than a certain percentage of neighbours light, so Ando crafted the form until he found the ideal solution.