Koichi Hirose is a fictional character from the popular manga and anime series JoJo's Bizarre Adventure. He is introduced in the fourth part of the series, titled Diamond is Unbreakable, where he plays a significant role as a high school student with a unique ability. Hirose possesses a Stand named Echoes, which allows him to manipulate sound and create various effects. His character is known for his friendly personality and strong sense of justice, making him a beloved figure among fans of the series.