Reunited with her beloved in both passion and purpose, Aya decides to join Toya in the quest for his real memories. A visit to an island where Aya spent a summer in childhood promises one of their first real leads to that end - it seems that Aya and Toya met long before, back when she was a little girl with a seashell, and when he... looked just exactly the same as he does now!
Despite not knowing who or even what Toya may be, the two decide to travel back to kindly Doctor Kurozuka in Niigata Prefecture to make a life. But Kagami is still on the hunt for Ceres' hagoromo, and closer to it than ever before. For every great advance, there must be an equally great sacrifice...