Kenji Onuma had the following podium finishes at major championships: 2nd in the 1958 Asian Games Middleweight class. He set one world record in the clean & jerk.
| Games | Discipline (Sport) / Event | NOC / Team | Pos | Medal | As | |
|---|---|---|---|---|---|---|
| 1956 Summer Olympics | Weightlifting | Kenji Onuma | ||||
| Lightweight, Men (Olympic) | 4 | |||||
| 1960 Summer Olympics | Weightlifting | Kenji Onuma | ||||
| Lightweight, Men (Olympic) |