SDN48 (read "S.D.N. Forty-eight", short for Saturday Night 48) was a Japanese idol girl group, created and produced by Yasushi Akimoto. SDN48 was created based on an "adult idol" concept. Former AKB48 member Kayo Noro was chosen as the captain of the group. In November 2010, the group made their major label debut with "Gagaga". The group ended with a farewell concert on March 31, 2012.

Source: Wikipedia (https://en.wikipedia.org/wiki/SDN48)