Famitsu has a short description of the event:
“Anime + Game”
New “Anime x Sega” Project Presentation on March 21 between 12:00 and 13:00. Sega will announce a new game and anime collaboration project. Featuring girl band Nanamori-chu Goraku-bu members Shiori Mikami, Yuka Otsubo, Minami Tsuda, and Rumi Okubo.
AnimeJapan runs from March 20 to 21 at Tokyo Big Sight.