Rei Koito

Rei Koito is a university student, the older sister of Yuu Koito and the girlfriend of Hiro. Rei is a understanding and supportive sister to Yuu Koito, with whom she is close. She quickly comes to suspect Yuu's relationship with Touko Nanami is more than simply platonic and does her best to help them both with advice and support. When she isn't being serious, she enjoys affectionately teasing Yuu whenever she gets the chance.