Jakusoku oboeteru (E17)

After Riku falls of the train, Saya jumps off after him in attempt to save him. Now she is caught in a blizzard and collapses. While she is passed out, Saya dreams of her past and when she and Hagi were in Russia back in the 1920s. While looking for a man named Gregory, they meet a girl named Sonia. Though Sonia is an ordinary girl, there is more to her then meets the eye. (Prime Video)