Tokiwa

The protagonist's double in the second timeline. He's everything the protagonist used to be, including being the partner of Tsugumi, much to the protagonist's dismay.

Nearing the end of the story, he confronts the protagonist's stalking tendencies, and instead of being mad he gives him a full schedule of his future activities, including driving to a diner with Tsugumi. This, in turn, helps the protagonist remember about the car crash, saving both Tokiwa and Tsugumi, preventing a third cycle from happening.