AKB48 singer Yuko Oshima, 25, said she is "graduating" from the megapopular all-girl idol group.

Oshima made the surprise announcement after AKB48 finished their song "Koisuru Fortune Cookie" during NHK's "Kohaku Uta Gassen" music variety program on Tuesday night.

Oshima, who is captain of the group's Team K, joined AKB48 in 2006. She has placed in the top two in the past five AKB48 general elections. In the 2013 general election, she was voted second overall with 136,503 votes, losing to Rino Sashihara with 150,570 votes.

Other members of the group seemed surprised when Oshima made the announcement.

Although Oshima didn't mention the exact date of her "graduation," Japanese media speculated Wednesday that her farewell performance with AKB48 is likely to be at a concert scheduled for March at the National Stadium in Tokyo.

Oshima said afterwards that she hoped to work more as an actress and was looking forward to a solo career, Sports Nippon reported.

© Japan Today