Yui Furukawa
古川 ゆい
A first-year student who transferred to Uchihama Academy. She joined in the Astronomy Club after she met Sou.
It was later on revealed than she is from the future and was created by Sou to be sent back to the past to save Kaori from an impending accident. However, she has been to the past multiple times, where most of her attempts to save Kaori ended in failure.