Kobayashi Marina announces her graduation during a Team 4 theater concert, which took place the night of July 11th, 2015.

Here’s a video clip of the moment she announces it:

7/11b 小林茉里奈 卒業発表 pic.twitter.com/fSVvi06njM

— 755まとめ(手動) (@755BOT) July 11, 2015

The clip is cut short, however she explains that she has thought about graduating since since last year.

“There’s so many things I want to do. I want to focus on my studies, so I’ve decided to graduate from AKB48.”

“My future dream is to become an announcer.  I’ve always loved idols, and I’ve tried hard at both my studies and AKB48.  I’ve been in AKB48 for five years now, and while I can’t say it’s always been smooth sailing, I come to realize that (five years) is more than enough.”

Screen shots from the announcement itself. The girl in blue is Kato Rena, who is in the same generation; there is also a tweet from Iriyama Anna (again, same generation).

“Marina, in the same gen as me, announced her graduation.  I heard from Marina beforehand, but even so, I couldn’t relax coming to the theater.  It’s really a lonely feeling. Ever since I first me her, she’s always said her dream is to be an announcer, and I plan to support her.”