Time Spiral

A swirling spiral of space and time connecting the past and the future.
When Aizawa Natsuki was a child, she was kidnapped which left her severely & emotionally traumatized. Natsuki grew up relying on her friend Yuki Kentaro. She now studies physics at a university. One day, she meets newly appointed professor Tatsumi Shuya. From then on, mysterious events occur continuously around Natsuki. Shuya is a time traveller who travels between the future and the past.
What could be the fate of this hero and heroine?