Supersize girl group AKB48—which started with 48 vocal stars in 2005 and counted 120 members by 2015—can cheer up any day with their all-together-now vocal delivery and upbeat crowd pleasers. The outfit takes the cheery stylings of Japanese idol pop to their logical extreme: Dozens of singers incant the words of each song, adding extra force to a synth-driven sound. AKB48 excel at the optimistic, bringing sweetness to the string-accented disco sway of “Koisuru Fortune Cookie”. The swift “Heavy Rotation” is a sugar rush, and they flirt with darker moods on shadowy synth rumbler “UZA”.