| Japan - NPB - Reserveliga | 2021/09/05 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | L | 7-3 |
| Japan - NPB - Reserveliga | 2021/09/04 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | L | 7-4 |
| Japan - NPB - Reserveliga | 2021/07/25 07:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | L | 5-2 |
| Japan - NPB - Reserveliga | 2021/07/24 07:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | W | 2-3 |
| Japan - NPB - Reserveliga | 2021/07/23 07:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | L | 9-4 |
| Japan - NPB - Reserveliga | 2021/04/22 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | W | 0-14 |
| Japan - NPB - Reserveliga | 2021/03/24 04:00 | Yomiuri Giants - Reserve v Seibu Lions - Reserve | L | 1-2 |
| Japan - NPB - Reserveliga | 2021/03/23 04:00 | Yomiuri Giants - Reserve v Seibu Lions - Reserve | L | 0-1 |
| Japan - NPB - Reserveliga | 2021/09/29 07:00 | Nipponham Fighters - Reserve v Yomiuri Giants - Reserve | L | 13-7 |
| Japan - NPB - Reserveliga | 2021/09/28 07:00 | Nipponham Fighters - Reserve v Yomiuri Giants - Reserve | W | 0-6 |
| Japan - NPB - Reserveliga | 2021/09/20 04:00 | Yakult Swallows - Reserve v Yomiuri Giants - Reserve | L | 14-4 |
| Japan - NPB - Reserveliga | 2021/09/19 04:00 | Yakult Swallows - Reserve v Yomiuri Giants - Reserve | W | 3-4 |
| Japan - NPB - Reserveliga | 2021/09/08 04:00 | Yomiuri Giants - Reserve v Nipponham Fighters - Reserve | L | 4-8 |
| Japan - NPB - Reserveliga | 2021/09/07 04:00 | Yomiuri Giants - Reserve v Nipponham Fighters - Reserve | L | 0-8 |
| Japan - NPB - Reserveliga | 2021/09/05 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | L | 7-3 |
| Japan - NPB - Reserveliga | 2021/09/04 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | L | 7-4 |
| Japan - NPB - Reserveliga | 2021/09/20 04:00 | Chiba Lotte Marines - Reserve v Seibu Lions - Reserve | D | 0-0 |
| Japan - NPB - Reserveliga | 2021/09/13 08:45 | Rakuten Eagles - Reserve v Seibu Lions - Reserve | W | 1-4 |
| Japan - NPB - Reserveliga | 2021/09/11 04:00 | Rakuten Eagles - Reserve v Seibu Lions - Reserve | W | 0-2 |
| Japan - NPB - Reserveliga | 2021/09/05 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | W | 7-3 |
| Japan - NPB - Reserveliga | 2021/09/04 04:00 | Seibu Lions - Reserve v Yomiuri Giants - Reserve | W | 7-4 |
| Japan - NPB - Reserveliga | 2021/09/01 03:55 | Nipponham Fighters - Reserve v Seibu Lions - Reserve | W | 10-11 |
| Japan - NPB - Reserveliga | 2021/08/26 04:00 | Yakult Swallows - Reserve v Seibu Lions - Reserve | W | 3-8 |
| Japan - NPB - Reserveliga | 2021/08/25 04:00 | Yakult Swallows - Reserve v Seibu Lions - Reserve | L | 4-0 |