By 2015, the AKB48 sister-group system had proliferated into a full idol industrial complex. Nogizaka46, created as an official 'rival' to AKB48, emerged as a major force with three top-10 singles. The AKB48 election single 'Bokutachi wa Tatakawanai' was the year's top seller with over 1.7 million copies, reflecting the unique Japanese market where physical CD sales still dominated charts.
