Mano Erina graduation concert title 真野恵里菜メモリアルコンサート ｢OTOME LEGEND～For the Best Friends」 in Nakano Sun Plaza which held February 23rd 2013 for the ticket already sold out.
But, you can watch it at Nico Nico Douga. here's for the link....
afternoon 3:30pm 2/23
night 7pm 2/23
Make sure you already have Nico Nico account and buy the "internet ticket" at Nico Nico site for watch stream.
SO, prepare yourself for watch this graduation concert!