Saburou Koyama, also known as Chuck Olsen in the Spanish dub, is a field operative within the specialized Born Free Team. This expedition group actively protects resurgent dinosaurs emerging from environmental anomalies across the globe. Koyama participates directly in field missions alongside teammates Joji Kitayama, Akira Gonda, Reiko Maki, and Masao Masaki, confronting threats to these prehistoric creatures. His role remains steadfast throughout the narrative, with no documented individual backstory or character evolution across the series' episodes. No expanded material concerning his background or development exists beyond the original 1976-1977 television series.