Yuka

Yuka is Kouta's cousin. She is also around 19 years old and planning to attend the same university as Kouta. She moves in with him at the inn after having not seen him in many years. Having had a crush on Kouta since childhood, she is in love with him, and is therefore jealous of Kouta's attention to Nyū, to the point of being very irrational. (Source: Wikipedia) In the Anime In the Manga