During their first anniversary concert , Noro announced to the audience that SDN48 would debut under Universal Music in the fall . The group also suggested they would be eliminating the age restriction . Through their TV show , , SDN48 held a election to determine the top twelve members who would participate in their debut single . Former AKB48 member Megumi Ohori won No. 1 and was given the center position . The single would be titled " Gagaga " and be released on November 24 , 2010 . On September 30 , 2nd generation member Sakura Fukuyama announced through her blog that she would be leaving the group due to health problems . Chinese member Chen Qu was chosen as Fukuyama replacement . The group was scheduled to release their second single on 23 March 2011 ; however , due to the Tōhoku earthquake and tsunami on 11 March , the single was postponed until 6 April
Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
SDN48