Yamasato

Oota and Yamasato are classmates of Kaori and Hajime from elementary school.

[Spoiler] They were talking with Hajime and Yuuki in the family restaurant about the events that took place right before a car accident with Kaori. Turned out that Kaori's best friend Shigehara Naomi liked Hajime and hated that Kaori and Hajime got close together. Naomi overheard the conversation about their secret meeting on the day before Hajime transfers and set on a group of classmates to intercept Kaori on her way to Hajime and bully her to prevent their final meeting from happening. As a result Kaori ran away crying and got hit by the car. [/Spoiler]