When he wakes up, Setsuna has no memories. He is on the island left behind by time, Urashima. Everyone he meets is mysterious and puzzling. At night he is surprised by a girl singing on the beach, and somehow says her name.

Although it was by Karen's request, Setsuna does something unthinkable. They go to the mainland so that Karen can escape and go to see her mother. Why did she cry while Setsuna watched over her? Meanwhile, Sara is getting close to something.

When they awoke, they were looking up at the blue sky from five years ago. It was the mysterious island where Rinne and the real Setsuna had been before parting ways forever. Rinne feels excited to see the real Setsuna again and finally settle things, but what they find are more riddles, tears, and darkness.

Rinne and Rinne - A truth about these two girls is brought to light by a photograph, and Setsuna makes a decision. Will it make everyone happy? A new future awaits once this great mystery is solved. No more hesitating. It's the eternal finale.