|Manga Debut||Chapter 1|
|Anime Debut||Episode 1|
|Voiced by||Chika Anzai|
Koyuki is a high schooler, who lost her brother after saving her from an accident.
After lost her brother, she was filled with guilty and looking for a Horologue to revert the time. However, she was later figured out that Horologues are actually devouring the humanity's time. She stopped herself after discovered the truth from Kiri and Viktor. Moreover, she realized that she didn't lose her memories: the days she spent with her brother which considered as the most precious treasure.
- She is the main character in the one-shot.
- In the one-shot, however, she didn't lose her brother. Instead, she saved a young boy from an incident. As a result, she was injured and couldn't dance anymore with her friends. She could only watch them from afar. This regret resulting her to search for a Horologue to revert the time.