Asaba Hideaki is Arima's best friend and the only guy he seems to trust around Yukino. Initially the pair do not get along. Asaba talks to Arima in order to win his confidence and attract more female members of the school. Arima being the cool person he is talks back when spoken to but doesn't particularly care about Asaba for quite a while. It is not until Arima is late for a date with Yukino and Asaba helps relieve any possible tension the pair might have between them (by hanging Arima backwards off a bridge O_o) that the trio become a tighknit group.

Asaba comes from a rich family but lives alone. He often sleeps over at Yukino's house and teases Yukino by implying the two boys are more than just friends ^_~ He is a rather eccentric person and has an obsession for collecting girls so to speak. He's somewhat of a playboy and thinks he's very sexy. The girls at school most certainly don't disagree. ^_-

Although Asaba can be somewhat of a handful his relationship with Arima is quite important. When Arima is troubled by Yukino and Tonami's newfound friendship Asaba is one of very few people to notice. The scene on the rooftop (book 7) is one which I think is quite beautiful since Asaba shows just how concerned he is for his friend and acts more seriously than we have seen before. The only thing he says as he walks to the rooftop and sits down is "Daijoubu ka" (are you alright?). But it has all the more impact because of that. Arima says nothing, he simply leans on Asaba's back and looks at the sky.