The
new trailer for the second season has clips that are clearly from the Hakuou Gakuin sports festival arc from the manga (volume 6), and (as readers will know) is a pretty good indication that they're probably planning on doing the whole Valentine's Day arc this is a run up to.
Which is good news for me, since that also hints that the OVA was indeed a flash forward and we'll get our "How Ayumu and Hinagiku became friends" plot thread in here at last.