Hiroshi Nagai (永井 博, Nagai Hiroshi, born March 10, 1941 in Shanghai, China), better known by the pseudonym Yasutaka Nagai (永井 泰宇, Nagai Yasutaka), is a Chinese-born Japanese novelist, manga author and scenario writer. He is one of the four brothers of manga artist Go Nagai. When working as a comic writer, he usually takes yet another pen name, that of Hiroshi Koenji. He wrote several comics for both his brother Go Nagai and Ken Ishikawa, such as Maboroshi Panty, Haru Ichiban and Shinrei Tantei Occult Dan, among others.