Uzuki is Yuki’s former classmate in both middle and high school. A boy who has had a harsh life but finds peace in gardening and was Yuki's first "friend."
At some point, he became malicious, always frustrated, downright cruel towards Yuki, and didn't even take care of his dear flowers. It is revealed that he is been possessed by a Duras, causing him to act that way, and his possession is the first real experience with Duras that Yuki encounters.
Uzuki and Yuki in the aftermath.
Uzuki possessed.