AKB48 Team K's Oshima Yuko has announced her graduation from the group.
This was announced on December 31st during the broadcast of the '64th NHK Kohaku Uta Gassen'. After performing "Koisuru Fortune Cookie", Oshima suddenly announced her graduation, "This will be my last time appearing on Kohaku like this. I will sing wholeheartedly." The group then performed her center song "Heavy Rotation".
Oshima hadn't told the other members about her graduation before the announcement. Details on her graduation is still undecided.
Oshima made her theater debut as a member of Team K in April of 2006. She took the number one spot in the group's 2nd (2010) and 4th (2012) Senbatsu General Elections. She has expanded her activities by starring in various movies, tv shows, and dramas.
Source
Here's the video if anyone interested~