Koyanagi Yu is a Japanese actor and former drummer of the Japanese rock band ONE OK ROCK. He was the initial band drummer however he is not credited as a former member. He left the band in June 2006 to pursue the dream of being an actor. Koyanagi Yu is managed by Stardust.

小柳友，日本男演员，毕业于堀越高等学校，现为Stardust Promotion事务所所属。从3岁开始在母亲的建议下开始作为模特在杂志上活跃，在电视剧木更津猫眼中以演员出道。代表作品《我不能恋爱的理由》、《不良仔与眼镜妹》，电影《有天使的楼顶》、《赛罗奥特曼THEMOVIE超决战贝利亚银河帝国》。