I watched part of this earlier, but am I correct in assuming that this is a new OVA set in the middle of the original series? Looks like they were trying to say it was at the point where Mahoro has only 270 days left.
Is it just an “extra” adventure or is it an attempt to rewrite the end of the series? And what does Tadaima Okaeri mean? SFW didn’t bother to translate it, nor some signs and flashed graphics that might have been important.