Yamaguchi, Koutarou
Current rating: 1474
Record: 47-50
Grand Prix Kobe 2008Grand Prix Okayama 2008Grand Prix Kobe 2009Grand Prix Yokohama 2010Grand Prix Hiroshima 2011Grand Prix Yokohama 2012Grand Prix Nagoya 2012Grand Prix Yokohama 2013Grand Prix Shizuoka 2018 (standard)Grand Prix Yokohama 2019Regional Championships Aichi 2022Regional Championships Yokohama 2023Regional Championships Chiba 2023
| Regional Championships Chiba 2023 (pioneer) | starting rating: 1519 | |||
| round | table | opponent (rating) | result | Δrating |
| 1pioneer | 60 | Omori, Ken'ichirou (1776) | Lost 0-2 | -131506 |
| 2pioneer | 103 | Kumakura, Takayuki (1416) | Won 2-1 | +161522 |
| 3pioneer | 78 | Takahashi, Taro (1698) | Lost 0-2 | -151507 |
| 4pioneer | 67 | Ishiwata, Kouichi (1682) | Lost 1-2 | -141493 |
| 5pioneer | 999 | Matsuda, Hideyuki (1443) | Lost 0-2 | -191474 |
| top | average opponent: 1603record: 1-4 | new rating: 1474 | ||
| Regional Championships Yokohama 2023 (ONE standard) | starting rating: 1552 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 53 | Yoshioka, Hideki (1490) | Lost 1-2 | -191533 |
| 2standard | 62 | tanimura, yuma (1513) | Won 2-0 | +171550 |
| 3standard | 55 | Kawasaki, Hirotaka (1754) | Lost 1-2 | -141536 |
| 4standard | 71 | Okamura, Marei (1600) | Lost 0-2 | -171519 |
| top | average opponent: 1590record: 1-3 | new rating: 1519 | ||
| Regional Championships Aichi 2022 (pioneer) | starting rating: 1566 | |||
| round | table | opponent (rating) | result | Δrating |
| 1pioneer | 56 | Park, Chan (1500) | Won 2-1 | +171583 |
| 2pioneer | 19 | Tanaka, Yu (1646) | Lost 1-2 | -171566 |
| 3pioneer | 37 | Hannya, Yamato (1542) | Won 2-0 | +171583 |
| 4pioneer | 14 | Ebitani, Keisuke (1732) | Lost 1-2 | -151568 |
| 5pioneer | 65 | Oka, Yosuke (1678) | Lost 0-2 | -161552 |
| top | average opponent: 1620record: 2-3 | new rating: 1552 | ||
| Grand Prix Yokohama 2019 (modern) | starting rating: 1611 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 377 | Mizutani, Rintarou (1500) | Lost 0-2 | -201591 |
| 2modern | 804 | Kohira, Yoshitaka (1556) | Lost 1-2 | -181573 |
| 3modern | 1201 | Ayata, Seitaro (1466) | Lost 0-2 | -201553 |
| 4modern | 1154 | Wu, Shengzhen (1441) | Won 2-1 | +161569 |
| 5modern | 1039 | Kawaharada, Kosaku (1410) | Won 2-0 | +151584 |
| 6modern | 756 | Sekiguchi, Kota (1586) | Lost 0-2 | -181566 |
| top | average opponent: 1493record: 2-4 | new rating: 1566 | ||
| Grand Prix Shizuoka 2018 (standard) (GRN standard) | starting rating: 1602 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 709 | Ito, Takuya (1506) | Won 2-0 | +161618 |
| 2standard | 547 | Maruyama, Nobuhiro (1588) | Won 2-0 | +181636 |
| 3standard | 376 | Shimazaki, Ryota (1598) | Lost 1-2 | -191617 |
| 4standard | 551 | Suzuki, Kazuhiro 4218 (1484) | Won 2-1 | +161633 |
| 5standard | 530 | Yamamoto, Kohei 0859 (1497) | Lost 0-2 | -211612 |
| 6standard | 599 | Chan, Russell (1580) | Won 2-0 | +181630 |
| 7standard | 401 | Sakata, Naoya (1598) | Lost 1-2 | -191611 |
| top | average opponent: 1550record: 4-3 | new rating: 1611 | ||
| Grand Prix Yokohama 2013 (GTC limited) | starting rating: 1555 | |||
| round | table | opponent (rating) | result | Δrating |
| 3sealed | 137 | Matsumura, Takehiko (1444) | Won 2-0 | +161571 |
| 4sealed | 20 | Nakagawa, Jin (1552) | Won 2-1 | +171588 |
| 5sealed | 29 | Bandou, Junichirou (1749) | Lost 1-2 | -151573 |
| 6sealed | 78 | Saitou, Keiichirou (1701) | Lost 1-2 | -151558 |
| 7sealed | 196 | Satou, Itaru (1545) | Won 2-0 | +171575 |
| 8sealed | 207 | Asakura, Takumi (1548) | Won 2-1 | +181593 |
| 9sealed | 276 | Minemura, Hiroyuki (1570) | Won 2-1 | +171610 |
| 10sealed | 110 | Yasuda, Seita (1556) | Won 2-0 | +171627 |
| 11sealed | 26 | Miyazaki, Kodai (1661) | Lost 1-2 | -171610 |
| 12draft | 58 | Iwasawa, Fumiya (1570) | Won 2-1 | +171627 |
| 13draft | 49 | Morofuji, Takuma (1932) | Lost 1-2 | -121615 |
| 14draft | 53 | Kojima, Tsubasa (1602) | Won 2-0 | +181633 |
| 15draft | 87 | Kanno, Atsushi (1745) | Lost 1-2 | -161617 |
| 16draft | 56 | Sugiyama, Yuya (1820) | Lost 0-2 | -151602 |
| top | average opponent: 1642record: 8-6 | new rating: 1602 | ||
| Grand Prix Nagoya 2012 (RTR standard) | starting rating: 1552 | |||
| round | table | opponent (rating) | result | Δrating |
| 3standard | 227 | Hoshino, Masaaki (1558) | Lost 0-2 | -181534 |
| 4standard | 304 | Murasawa, Yuuya (1498) | Won 2-0 | +171551 |
| 5standard | 309 | Hatano, Kaigo (1532) | Won 2-0 | +181569 |
| 6standard | 235 | Chen, Liang (1842) | Lost 0-2 | -131556 |
| 7standard | 287 | Hosomi, Kyouhei (1534) | Won 2-1 | +171573 |
| 8standard | 247 | Inoue, Shota (1551) | Lost 1-2 | -181555 |
| top | average opponent: 1586record: 3-3 | new rating: 1555 | ||
| Grand Prix Yokohama 2012 (modern) | starting rating: 1566 | |||
| round | table | opponent (rating) | result | Δrating |
| 2modern | 276 | Endou, Yuusuke (1804) | Won 2-0 | +221588 |
| 3modern | 254 | Nose, Koji (1828) | Lost 1-2 | -141574 |
| 4modern | 373 | Ooshima, Kunihiro (1581) | Lost 1-2 | -171557 |
| 5modern | 407 | Ashizawa, Yoshisato (1503) | Lost 0-2 | -191538 |
| 6modern | 473 | Miura, Hiroki (1455) | Won 2-1 | +161554 |
| 7modern | 413 | Kimura, Shigeki (1464) | Won 2-1 | +161570 |
| 8modern | 240 | Kawamura, Naoki (1524) | Lost 1-2 | -181552 |
| top | average opponent: 1594record: 3-4 | new rating: 1552 | ||
| Grand Prix Hiroshima 2011 (ISD standard) | starting rating: 1543 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 148 | Mori, Daisuke (1509) | Won 2-0 | +171560 |
| 2standard | 31 | Matsubara, Takeyuki (1500) | Won 2-1 | +171577 |
| 3standard | 44 | Yuba, Hirofumi (1540) | Won 2-0 | +171594 |
| 4standard | 58 | Kawate, Junpei (1610) | Won 2-1 | +191613 |
| 5standard | 35 | Furugen, Takeji (1521) | Won 2-0 | +161629 |
| 6standard | 13 | Nakajima, Chikara (2007) | Lost 0-2 | -111618 |
| 7standard | 49 | Matsumoto, Fumiya (1682) | Won 2-1 | +191637 |
| 8standard | 14 | Yamauchi, Satoshi (1593) | Won 2-1 | +171654 |
| 9standard | 22 | Tanaka, Kouichi (1611) | Lost 0-2 | -191635 |
| 10standard | 36 | Nakazono, Kouya (1599) | Lost 1-2 | -181617 |
| 11standard | 47 | Kitayama, Masaya (1864) | Won 2-1 | +221639 |
| 12standard | 37 | Wada, Hiroya (1678) | Lost 1-2 | -171622 |
| 13standard | 42 | Takahashi, Kazuya (1530) | Lost 0-2 | -201602 |
| 14standard | 44 | Nakamura, Junya (1643) | Lost 0-2 | -171585 |
| 15standard | 48 | Iwaide, Yoshitaka (1537) | Lost 1-2 | -191566 |
| top | average opponent: 1628record: 8-7 | new rating: 1566 | ||
| Grand Prix Yokohama 2010 (extended) | starting rating: 1584 | |||
| round | table | opponent (rating) | result | Δrating |
| 1extended | 318 | Nakamura, Yuichiro (1599) | Won 2-0 | +181602 |
| 2extended | 205 | Wen, Yuning (1563) | Lost 0-2 | -181584 |
| 3extended | 221 | Hasegawa, Baku (1430) | Lost 0-2 | -211563 |
| 4extended | 415 | Date, Hideyuki (1445) | Lost 1-2 | -201543 |
| top | average opponent: 1509record: 1-3 | new rating: 1543 | ||
| Grand Prix Kobe 2009 (extended) | starting rating: 1584 | |||
| round | table | opponent (rating) | result | Δrating |
| 2extended | 141 | Hashizume, Yuuya (1574) | Lost 0-2 | -181566 |
| 3extended | 173 | Yasuda, Taiga (1467) | Lost 1-2 | -201546 |
| 4extended | 206 | Yamada, Hiroki (1590) | Won 2-1 | +191565 |
| 5extended | 193 | Sakamoto, Sakito (1492) | Won 2-0 | +171582 |
| 6extended | 154 | Kashima, Akihiro (1719) | Won 2-1 | +201602 |
| 7extended | 118 | Takao, Akinao (1604) | Lost 1-2 | -181584 |
| top | average opponent: 1575record: 3-3 | new rating: 1584 | ||
| Grand Prix Okayama 2008 (ALA limited) | starting rating: 1624 | |||
| round | table | opponent (rating) | result | Δrating |
| 2sealed | 84 | Umeno, Kengo (1716) | Lost 0-2 | -161608 |
| 3sealed | 203 | Watanabe, Yoshifumi (1487) | Lost 1-2 | -211587 |
| 4sealed | 213 | Kaneko, Naoto (1486) | Won 2-1 | +171604 |
| 5sealed | 172 | Takao, Akinao (1527) | Lost 1-2 | -201584 |
| top | average opponent: 1554record: 1-3 | new rating: 1584 | ||
| Grand Prix Kobe 2008 (Lorwyn block) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1block | 28 | Ito, Ken (1638) | Won 2-1 | +211521 |
| 2block | 56 | Han, Hojae (1523) | Won 2-0 | +181539 |
| 3block | 75 | Matsuda, Issui (1583) | Won 2-0 | +181557 |
| 4block | 23 | Nakajima, Chikara (1565) | Lost 0-2 | -181539 |
| 5block | 137 | Naitou, Keisuke (1683) | Won 2-0 | +211560 |
| 6block | 73 | Tamai, Katsuyoshi (1575) | Won 2-1 | +181578 |
| 7block | 14 | Kinoshita, Atsushi (1530) | Won 2-1 | +181596 |
| 8block | 32 | Udagawa, Hisashi (1609) | Lost 1-2 | -181578 |
| 9block | 68 | Matsuoka, Tomohide (1664) | ID | 01578 |
| 10block | 58 | Yamada, Yasushi (1559) | Lost 1-2 | -191559 |
| 11block | 62 | Kawamura, Kazushi (1783) | Lost 1-2 | -141545 |
| 12block | 62 | Nakamura, Yuichiro (1647) | Won 2-0 | +201565 |
| 13block | 56 | Shimizu, Kenji (1559) | Won 2-0 | +181583 |
| 14block | 37 | Saito, Takaya (1673) | Won 2-1 | +201603 |
| 15block | 6 | Hirayama, Daisuke (1775) | Won 2-0 | +211624 |
| top | average opponent: 1624record: 10-4-1 | new rating: 1624 | ||