| T2 Diamond | 11/21 13:15 | - | Koki Niwa v Hugo Calderano | W | 4-2 | |
| Austrian Open | 11/16 15:50 | 3 | Hugo Calderano v Koki Niwa | L | 4-2 | |
| Austrian Open | 11/15 16:50 | 4 | Koki Niwa v Mattias Falck | W | 4-2 | |
| Austrian Open | 11/14 17:20 | 5 | Koki Niwa v Benedikt Duda | W | 4-2 | |
| Team World Cup | 11/06 09:00 | - | Koki Niwa v Daniel Habesohn | W | 3-2 | |
| Team World Cup | 11/06 03:30 | - | Liam Pitchford v Koki Niwa | L | 3-0 | |
| German Open | 10/11 16:40 | 4 | Youngsik Jeoung v Koki Niwa | L | 4-3 | |
| German Open | 10/10 14:40 | 5 | Kenta Matsudaira v Koki Niwa | W | 1-4 | |
| Swedish Open | 10/04 16:00 | 4 | Koki Niwa v Simon Gauzy | L | 2-4 | |
| Swedish Open | 10/03 18:30 | 5 | Koki Niwa v Takuya Jin | W | 4-2 | |
| Paraguay Open | 09/12 18:00 | - | Koki Niwa v Kai Zhang | L | 2-4 | |
| Japan - T. League | 09/06 11:02 | - | Chen Chien An v Koki Niwa | W | 2-3 | |
| Japan - T. League | 08/31 09:30 | - | Koki Niwa v Chien An Chen | W | 3-0 | |
| Czech Open | 08/22 14:20 | 5 | Marcos Freitas v Koki Niwa | L | 4-1 | |
| Bulgaria Open | 08/15 13:45 | 5 | Marcos Freitas v Koki Niwa | L | 4-0 | |
| T2 Diamond | 07/19 10:00 | - | Koki Niwa v Mattias Falck | L | 2-4 | |
| Austrailia Open | 07/11 07:30 | 5 | Koki Niwa v Yun-Ju Lin | L | 3-4 | |
| Korea Open | 07/04 11:20 | 5 | Seungmin Cho v Koki Niwa | L | 4-1 | |
| Japan Open | 06/14 04:20 | 5 | Kazuhiro Yoshimura v Koki Niwa | L | 4-2 | |
| Hong Kong Open | 06/07 11:10 | 4 | Koki Niwa v Jun Mizutani | L | 2-4 | |
| Hong Kong Open | 06/06 08:50 | 5 | Koki Niwa v Sathiyan Gnanasekaran | W | 4-1 | |
| China Open | 05/31 12:30 | 4 | Long Ma v Koki Niwa | L | 4-0 | |
| China Open | 05/30 08:55 | 5 | Kazuhiro Yoshimura v Koki Niwa | W | 0-4 | |
| World Championship | 04/26 10:45 | 3 | Jingkun Liang v Koki Niwa | L | 4-3 | |
| World Championship | 04/25 09:00 | 4 | Tomislav Pucar v Koki Niwa | W | 2-4 | |
| World Championship | 04/24 15:00 | 5 | Jakub Dyjas v Koki Niwa | W | 1-4 | |
| World Championship | 04/23 17:50 | 6 | Paul Drinkhall v Koki Niwa | W | 0-4 | |
| World Championship | 04/23 12:50 | 57 | Marcelo Aguirre v Koki Niwa | W | 1-4 | |
| Qatar Open - Damer | 03/29 15:30 | 4 | Patrick Franziska v Koki Niwa | L | 4-3 | |
| Qatar Open - Damer | 03/28 14:35 | 5 | Maharu Yoshimura v Koki Niwa | W | 2-4 |
Wikipedia - Koki Niwa
Koki Niwa, född den 10 oktober 1994 i Tomakomai, är en japansk bordtennisspelare.
Han tog OS-silver i herrlag i samband med de olympiska bordtennisturneringarna 2016 i Rio de Janeiro. Vid lagtävlingen under sommarspelen 2020 i Tokyo tog han en bronsmedalj.