The opening animation PV for Hachigatsu no Cinderella Nine, a mobile game app where you train/raise a group of high school girls to become baseball athletes so that they can make it to Koshien. The game was launched the following month for both iOS and Android.
Watch Hachigatsu no Cinderella Nine (ONA) episode 1 online — subbed and dubbed, with automatic AniList / MyAnimeList progress sync.