Kotegawa Yū

Yuu Kotegawa is Yui's older brother, and a ladies' man, which she dislikes about him. However  at the moment, he is dating  Akiho ,  Haruna Sairenji 's older sister, but unknown to him she isn't taking the relationship as seriously as he does. [14]

Appearance
Yuu is a tall and fit young man who has light brown hair and gray eyes.

Personality
Yuu is quite calm and easy going, he is also very protective of women when he see's them in trouble. He enjoys teasing his sister about her relationship with Rito, like mentioning him in front of her and their parents.

Biography
After finding Rito and Yui being chased by hoodlums, he defends the two of them from the ruffians, while commenting that he hopes Yui will grow to be more mature.[13] Since then, he has taken notice of Yui's relationship with Rito. He can easily read his sister's poorly hidden feelings and her love for Rito, and is eager to see his sister become more open to romance through Rito.

Yui Kotegawa
Yui is his little sister, she greatly dislikes how he can be a lady's man and how he always brings up Rito in front of her which she occasionly over reacts and blushes, something he enjoys teasing her about. Yuu hopes that she will be more mature and accept her love for Rito.

Rito Yuuki
In thier first meeting Rito thought that he looked cool. He seems to understand more about Rito's life and all the misfortunes happening around him which is another thing he like's about him, he is one of the few people who knows that Riko Yuusaki is in fact Rito, Yuu claims that at least his life is more exciting. He would often mention his name at home in front of Yui just to make fun of her.

Akiho Sairenji
Akiho is someone Yuu is currently dating but she isn't taking it as seriously he does and feels disapointed by every time she blows him off whenever he asks her out.