He had an illustrious career spanning 18 years with the Hokkaido Nippon-Ham Fighters, Yomiuri Giants, and the Chunichi Dragons where he won two Japan Series, two MVP awards in both the Pacific and Central leagues; only one of two people to do so and the first to do it in consecutive seasons.

When he started at the team he was regarded as a complete no-name and his then coach mentioned that "we were asked to go after a junior middle schooler from the Chiba West Little League and we got the player that no one spoke of, Ogasawara.

In 1996, he took part in the 67th Intercity baseball tournament, playing alongside Nobuhiko Matsunaka with Nippon Steel & Sumitomo Metal Kazusa Magic to reach the best 8.

He also played for the Japanese national team in the 2006 World Baseball Classic, where he hit a home run off Esteban Loaiza at Angel Stadium of Anaheim.

In 2006, he helped the Hokkaido Nippon-Ham Fighters win their first Pacific League pennant since 1981, sweeping the Fukuoka SoftBank Hawks in the playoffs to reach the Japanese championship series against the Chunichi Dragons.