Reunited with her beloved in both passion and purpose, Aya decides to join Tôya 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 - turns out Aya and Tôya 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 Tôya may be, the two decide to travel back to kindly Doctor Kurozuka in Niigata Prefecture to make a life for themselves there. But Kagami is still on the hunt for Ceres' hagoromo, and is in fact even closer to it than ever before. For every great advance, there must be an equally great sacrifice - how will Chidori figure into it?