AKB48 (pronounced A.K.B. Forty-eight) are a Japanese idol girl group named after the Akihabara (Akiba for short) area in Tokyo, where the group's theater is located. The group has expanded since then to include over 130 members as of December 2015, aged from their early teens to their mid-20s. AKB48's producer, Yasushi Akimoto, wanted to form a girl group with its own theater (unlike pop groups performing occasional concerts and seen on television) and performing daily so fans could always see them live. This "idols you can meet" concept includes teams which can rotate performances and perform simultaneously at several events and "handshake" events, where fans can meet group members.

The group has publicized special events to choose the promotional and recording lineups for some of its singles. In 2009, the concept of senbatsu sosenkyo (Xuan Ba Zong Xuan Ju , "selection general election") was introduced, which allowed fans to vote their favorite members into the promotional line up or senbatsu (Xuan Ba , "selection") for one of their annual singles. Ballots are obtained by purchasing the group's latest "election single", or, alternatively, through the group's mobile app products and fan club subscriptions. Top vote getting members are heavily promoted, with the winner getting the centerpiece of the group's live performances of the single. The total pool of votes counted has exceeded three million votes for individual events since 2015. Fans have reportedly bought hundreds of copies of singles to vote for their favorite members.  Another selection method, AKB48's rock-paper-scissors tournaments, was introduced in 2010 for the group's 19th single ("Chance no Junban") and has recurred as an annual event. Members of AKB48 and its sister groups compete in the knockout tournament to be part of the recording and promotional lineup for the group's next single, with participants wearing a variety of costumes. Starting with 2014, the tournament does not determine the promotional line up of a single anymore. Instead, the winner would debut as a soloist or, if she was already a soloist, would perform a solo concert.  AKB48 has also used the general election scheme to determine set lists for an annual Request Hour (rikuesutoawa, rikuesuto awa) show. Other annual events include an AKB48 group only version of Kohaku Uta Gassen and the AKB group draft meeting (AKB48gurupu dorahutoHui Yi , AKB48 gurupu dorafuto kaigi), in which all teams from any of the sister groups chose new members from a pre-selected group of applicants.

what was the single?