Setsuna, Sara and Karen try various ways to get Rinne to come out during the day. Their fun time is interrupted when Rinne sees a hidden shack. After that, Rinne tries to stop thinking about the past, but Karen makes a decision to face it down.

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.

"I don't have time to spare!" Sara yells hurriedly. She has a hypothesis as to why Setsuna came back in time and that he and she are destined to be together, but Rinne confronts him with a dark truth. Crimson flames lick the heavens, bringing an end to a bloody history.

In an underground shelter-city encased in ice, Setsuna meets a young girl named Rinne and begins helping her with a mysterious invention. It can apparently help save the world, but its true nature is unclear. Meanwhile, the city itself will very soon perish.