Kojima Haruna's graduation concert "Koji Matsuri ~Kojima Haruna Kanshasai~" will be held on February 22, 2017 at Yoyogi National Gymnasium. 

This announcement was made during "Kojima Haruna Kinkyuu Namahousou Special" on SHOWROOM. Kojima referred to the day as "Nyan Nyan Nyan Day" and explained the concert title, "It's a concert, but I want it to be like a festival." 

There are also plans for an event to be held the night before the graduation concert on February 21. More details will be revealed in the near future.

Source: natalie