Shimomura spent his early career as a magazine writer and an assistant director for non-scripted TV shows. As a freelance scripted-content production staff, he was involved in numerous blockbusters, including Shizumanu Taiyo (The Never-Setting Sun, 2009),  Parasyte: Part 1 (2014), Parasyte: Part 2 (2015), A Man Called Pirate (2016), March Comes in Like a Lion 1 and 2 (2017). Shimomura worked as a line producer for Million Dollar Man (2018), The Fable: The Killer Who Doesn't Kill (2021)  and the Netflix series YuYu Hakusho (2023). Yu Yu Hakusho (2023) has become the biggest global hit ever for a series from Japan, captivating audiences worldwide in the first week since its global release. It debuted at #1 in the Netflix Weekly Global Top 10 Non-English TV List, and secured the second spot across both English and non-English categories. In addition, the series also made the Top 10 in 92 countries and regions around the world. Joined THE SEVEN in January 2024.