Keishi Nagatsuka is a Japanese actor, voice actor, screenwriter, and theater artist. Born on March 9, 1975, in Tokyo, he is the son of actor Kyozo Nagatsuka and is married to actress Takako Tokiwa. Nagatsuka is a graduate of Waseda University and a key member of the theater production group Asagaya Spiders, where he works as both an actor and an artistic director.

While Nagatsuka has an extensive career in live-action film and television, he has also taken on significant voice acting roles in anime and special effects productions. In the realm of animation, he is known for his role as Kyuta's father in the 2015 anime feature film The Boy and the Beast, directed by Mamoru Hosoda. In live-action cinema with voice components, he portrayed the character Hayasaka in the 2022 tokusatsu film Shin Ultraman, a role that required voice performance as part of the ensemble cast.

His voice work extends to other media as well. In 2019, he provided narration for the documentary film Documentary Literature: The Story of Seijun and Kyoko Oe in the Castle Town Where They Lived for 60 Years Making Movies. He has also worked as a screenwriter, contributing scripts for the television program Shukan Maki Yoko in 2008 and the film On the Edge of the River in 2021, demonstrating a career that spans multiple aspects of entertainment production.