When time gets twisted, it tries to go back to the original position. However, if one does it right in changing the course of time, such a twist does not occur. To me, it's hard to tell what is "doing things the right way"...
(Spoiler)
Shu'uya contemplates whether to go back 15 years ago, and leaves young Natsuki with the kidnappers. He starts to believe in what his colleague, a physics professor told him... that changing the course of time doesn't lead to parallel worlds which are independent of one another. Instead, those worlds are closely connected, and a person who exist in different worlds may have the same knowledge and information on things.
While Shu'uya decides to go back to the kidnapping incident and not to save Natsuki from the kidnappers, Natsuki tells her mother that she's to be killed by the kidnappers, but she (the mother) should overcome with the sadness of losing Natsuki by continuing her research on a new drug. Natsuki thinks if she encourages her mother in this world, the encouragement will go over to the other world in which Natsuki is killed.
Shu'uya goes back 15 years ago and meets young Natsuki. Instead of saving her, he tells her that she's a strong kid and should go for her own future. He gives her a hint to escape from the kidnappers, and then he goes back to 2020.
Shu'uya calls Mami. She is alive and answers the phone. She just came back from her honeymoon with Kentarou. Shu'uya is relieved to know Mami exists in 2020.
Shu'uya hurries to the university to look for Natsuki. He finally finds Natsuki who is working on her research on the spiral theory. Although this Natsuki has never met Shu'uya before, she stops him when he was leaving. She says, "Are you Prof. Tatsumi?" "I think I remember you... that we had lunch together."
Looking at Shu'uya, she says, "You're smiling." Shu'uya answers, "It's all thanks to you."
So, the future is bright! Natsuki and Shu'uya did the right preparation.
Time Spiral Ep.7
Time Spiral Ep.6
Time Spiral Ep.5
Time Spiral Ep.4
Time Spiral Ep.3
Time Spiral Ep.2
Time Spiral Ep.1
Time Spiral Premiers on Sept 2
Time Spiral
