The October issue of B-LOG confirms that Yuka Saitou will play the voice of Haru Asagi, the heroine of the game. She played a lot of minor roles but secured a main role as Chizuru Akabe from Seitokai no Ichizon. I only heard her roles in two animes that I’ve watched (Shiki and Umineko) so, I guess her role as Haru will be another starting point of her career.
Oh, if you haven’t seen it yet, the PV of the OVA is out on the official site. And Annabel, who did the ED themes of the games, is going to do the OP for the OVA.