This is an automatically translated description

It turns out that not only Naho received a letter from the future... Suwa also found a message in the mail calling for Kakeru's rescue. He is ready to act.

They unite for the sake of Kakeru, but when the two of them undertake to change the present, the instructions from the future no longer keep up with the series of events.

What to do now? How not to make a mistake in trying to prevent a tragedy and not to make things worse? And how not to harm the future, in which they, though tormented by remorse, are happy in their own way.