Premieres in Japanese theaters October 24th. The new PV is here. Check out the ANN article for additional information. Synopsis for the first season from AniList:
A typical morning. The usual music. Their normal lives. The peace these seven girls experience will suddenly be destroyed. By the living dead… zombies. A reality that they never wanted a part of, an amazing and terrifying zombie world. They all share one wish: “We want to live.” These girls will struggle through this saga, in order to achieve a miracle. MAPPA, Avex Pictures, and Cygames team up to bring you a juicy, 100% original anime. A timeless shocker for all audiences, a brand new style of zombie anime, will soon rise.
I am of two minds with this spoiler. This either makes or breaks the character depending on how it’s handled. From the top of my head, I cannot think of an instance where it turned out to be good when a “mysterious character” was suddenly given a main role treatment (looking at you Star Wars franchise).