Sogabe is one of Kou's best friends from before he was convicted of murder. He is the more calm and level headed one of the group and doesn't really get excited or worked up in any situation. Even when he finds his friend with a dead body, he just calmly calls the police to report a murder. He appears to be more of the leader of the group and is the one that instigates the investigation into if Kou actually murdered someone or not.

He is a 15 year old just like Kou, but I do picture his voice being more mature sounding due to his temperament and personality. He should have probably a medium to maybe deeper toned voice as well.