Here is the trailer:
Back in September 2017, VanillaWare was hiring programmers and designers for work on 13 Sentinels: Aegis Rim, as well as a second, unannounced project.
13 Sentinels: Aegis Rim Prologue launched for PlayStation 4 today in Japan. It features the first three hours of the full game, which is due out this fall in Japan. A western release is also planned, but has yet to be dated.
Thanks, Persona Central.
Update 11:26 p.m.: A newly published gameplay video of 13 Sentinels: Aegis Rim Prologue featuring freelance writer Mafia Kajita confirms (at 12:09) that details on the new project will be announced after the completion of 13 Sentinels: Aegis Rim. Watch that below.