Okubyou na Yubisaki

Hashibami recently lost his older brother, Isao, to a tragic traffic accident. Though he pretends he doesn't care, deep down he is greatly hurt by it. He meets Ashino, a charming student who goes to the same school as he does. He later finds out that Ashino is connected to his brother Isao. What is his connection to Isao? Why is it bothering Hashibami so much?