Imagine if J-Pop had its own massive Vegas-style revue in the heart of Tokyo. Meet AKB48, a girl group that boasts nearly 150 members – divided into five teams and distinguished by wardrobe color, with ages ranging from 12 to 37 – and performs daily at its own theatre. The Guinness World Record holder for Largest Pop Group, AKB48 is a phenomenon in Japan because their success spans so many platforms: live performances, studio albums, video games and television, etc. It's not just a gimmick though, as Japan genuinely loves the group's music: AKB48 has won Billboard Japan's Top Pop Artists award four straight years, and they have the most million-selling singles in Japanese history. Despite unprecedented popularity in Japan, they're mostly obscure over here. In fact, most Americans' first exposure to the girl group came last month when news spread that a saw-wielding man had attacked two members of AKB48 at a fan meet-and-greet in Japan.