| Koichi Oshima | |
| Position: | Coach / Infielder |
| Birth Date: | 17 June 1967 |
| Birth Place: | Itabashi, Tokyo, Japan |
| Bats: | Switch |
| Throws: | Right |
| Debutleague: | NPB |
| Debutdate: | April 18 |
| Debutyear: | 1993 |
| Debutteam: | Kintetsu Buffaloes |
| Finalleague: | NPB |
| Finaldate: | September 28 |
| Finalyear: | 2005 |
| Finalteam: | Tohoku Rakuten Golden Eagles |
| Statleague: | NPB |
| Stat1label: | Batting average |
| Stat1value: | .261 |
| Stat2label: | Hits |
| Stat2value: | 1088 |
| Stat3label: | Runs batted in |
| Stat3value: | 334 |
| Stat4label: | Stolen Bases |
| Stat4value: | 71 |
| Stat5label: | Home runs |
| Stat5value: | 24 |
| Teams: | As player
As coach
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| Awards: |
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is a retired Japanese professional baseball player from Itabashi, Tokyo, Japan. He played for the Kintetsu Buffaloes, Orix Buffaloes, and Tohoku Rakuten Golden Eagles during his professional career, and currently works as a minor league hitting coach for the Orix Buffaloes.
Oshima was a valuable switch hitter and a solid fielder, winning three Japanese golden glove awards at second base, and two Best Nine awards. He dismissed an offer to work as a coach when the Osaka Kintetsu Buffaloes and Orix BlueWave merged, and played a season with the Tohoku Rakuten Golden Eagles before becoming a coach for the Orix Buffaloes in 2006.
He won a bronze medal in the 1992 Summer Olympics before entering the Japanese professional leagues.