Koseki, Takefumi
Current rating: 1548
Record: 11-8
| Grand Prix Nagoya 2020 (pioneer) | starting rating: 1554 | |||
| round | table | opponent (rating) | result | Δrating |
| 1pioneer | 221 | Muramatsu, Hidefumi (1500) | Lost 1-2 | -191535 |
| 2pioneer | 561 | Ashizawa, Yoshisato (1294) | Won 2-1 | +131548 |
| 3pioneer | 572 | Sonoda, Kenichi (1367) | Won 2-0 | +151563 |
| 4pioneer | 422 | Sano, Masayo (1392) | Won 2-1 | +151578 |
| 5pioneer | 285 | Ikeda, Yuuki (1596) | Lost 0-2 | -181560 |
| 6pioneer | 291 | Saitou, Ryuuga (1906) | Lost 0-2 | -121548 |
| average opponent: 1509record: 3-3 | new rating: 1548 | |||
| Grand Prix Yokohama 2019 (modern) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 506 | Ueda, Takushi (1462) | Won 2-0 | +171517 |
| 2modern | 297 | Choi, Kiho (1666) | Won 2-1 | +211538 |
| 3modern | 336 | Muneishi, Hideaki (1471) | Lost 0-2 | -191519 |
| 4modern | 743 | Eto, Junpei (1437) | Won 2-1 | +161535 |
| 5modern | 518 | Sugaya, Yuta (1486) | Won 2-1 | +171552 |
| 6modern | 111 | Ishida, Shoichi (1434) | Won 2-1 | +161568 |
| 7modern | 52 | Sakamoto, Kazuma (1522) | Lost 0-2 | -191549 |
| 8modern | 179 | Watanabe, Ryoji (1598) | Won 2-1 | +191568 |
| 9modern | 190 | Liu, Xuan (1762) | Won 2-1 | +221590 |
| 10modern | 71 | Sawada, Ryo (1462) | Lost 1-2 | -211569 |
| 11modern | 100 | Kudou, Takunori (1653) | Won 2-1 | +201589 |
| 12modern | 131 | Tanaka, Hayato (1629) | Lost 1-2 | -171572 |
| 13modern | 144 | Kanbayashi, Taichi (1562) | Lost 1-2 | -181554 |
| average opponent: 1550record: 8-5 | new rating: 1554 | |||