18-year-old Takeya is fed up with his cute and whimsical friend, Ayumi, and her obsession with "angels", mysterious beings only known from urban legends. For a glimpse at their existence, she forces Takeya into investigating the recent surge of supernatural incidents, much to his annoyance. But when they finally corner a real-life angel in their snow-laden city, Takeya discovers that there is much more to his world than meets the eye–and that its end is nigh. After finding out the earth-shattering truth, he must team up with the angels he met to prevent the world's destruction. Because if they can't create a miracle, this will be the last winter they ever see.