Koshiishi, Tadahito
Current rating: 1588
Record: 50-46-1
Grand Prix Yokohama 2012Grand Prix Nagoya 2012Grand Prix Yokohama 2013Grand Prix Kitakyushu 2013Grand Prix Nagoya 2014Grand Prix Kobe 2014Grand Prix Shizuoka 2015Grand Prix Kobe 2015Grand Prix Nagoya 2016Grand Prix Tokyo 2016Grand Prix Kobe 2017Grand Prix Yokohama 2019Grand Prix Chiba 2019Grand Prix Nagoya 2020
| Grand Prix Nagoya 2020 (pioneer) | starting rating: 1546 | |||
| round | table | opponent (rating) | result | Δrating |
| 1pioneer | 420 | Kunuki, Yousuke (1528) | Won 2-1 | +181564 |
| 2pioneer | 256 | Yajima, Hiromichi (1446) | Won 2-0 | +161580 |
| 3pioneer | 374 | Renaud, Luke (1732) | Won 2-0 | +211601 |
| 4pioneer | 148 | Sasaki, Shimon (1626) | Lost 0-2 | -181583 |
| 5pioneer | 154 | Urabe, Ryosuke (1531) | Won 2-1 | +171600 |
| 6pioneer | 185 | Ikeda, Takahiro (1766) | Won 2-0 | +211621 |
| 7pioneer | 50 | Masumoto, Kazuhiro (1597) | Lost 0-2 | -181603 |
| 8pioneer | 227 | Nomura, Hidehiro (1771) | Lost 1-2 | -151588 |
| top | average opponent: 1625record: 5-3 | new rating: 1588 | ||
| Grand Prix Chiba 2019 (M20 limited) | starting rating: 1522 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 150 | Takamatsu, Tarou (1402) | Won 2-1 | +151537 |
| 2sealed | 169 | Miyahara, Hidetoh (1518) | Won 2-1 | +181555 |
| 3sealed | 193 | Yu, Yin (1799) | Lost 1-2 | -141541 |
| 4sealed | 373 | He, Yue 8578 (1794) | Won 2-0 | +231564 |
| 5sealed | 354 | Son, Kii (1573) | Won 2-1 | +181582 |
| 6sealed | 290 | Ikeda, Masahito (1558) | Lost 1-2 | -181564 |
| 7sealed | 455 | Suzuki, Towa (1596) | Lost 0-2 | -181546 |
| top | average opponent: 1606record: 4-3 | new rating: 1546 | ||
| Grand Prix Yokohama 2019 (modern) | starting rating: 1535 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 601 | Tozuka, Kouta (1678) | Won 2-0 | +201555 |
| 2modern | 133 | Yamada, Sintarou (1635) | Won 2-1 | +201575 |
| 3modern | 521 | Kojima, Terumasa (1699) | Lost 0-2 | -161559 |
| 4modern | 526 | Tsukuda, Kenta (1513) | Lost 1-2 | -191540 |
| 5modern | 836 | Makioka, Syuta (1512) | Lost 0-2 | -181522 |
| top | average opponent: 1607record: 2-3 | new rating: 1522 | ||
| Grand Prix Kobe 2017 (modern) | starting rating: 1499 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 751 | Taga, Tomonori (1500) | Draw 1-1 | 01499 |
| 2modern | 633 | Saka, Koichiro (1406) | Won 2-1 | +161515 |
| 3modern | 681 | Yuki, Kusuda (1518) | Won 2-0 | +181533 |
| 4modern | 355 | Shimazu, Youhei (1518) | Won 2-0 | +181551 |
| 5modern | 168 | Honda, Akihiro (1537) | Lost 1-2 | -181533 |
| 6modern | 398 | Serikawa, Emi (1548) | Won 2-0 | +181551 |
| 7modern | 242 | Lau, Wilfred (1634) | Lost 1-2 | -161535 |
| top | average opponent: 1523record: 4-2-1 | new rating: 1535 | ||
| Grand Prix Tokyo 2016 (SOI standard) | starting rating: 1501 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 1047 | Ohshiba, Atsushi (1465) | Won 2-0 | +171518 |
| 2standard | 368 | Sakano, Shuichi (1466) | Won 2-1 | +171535 |
| 3standard | 574 | Shirakawa, Yuichiro (1466) | Lost 1-2 | -191516 |
| 4standard | 1026 | Nakanishi, Yutaka (1485) | Lost 0-2 | -191497 |
| 5standard | 786 | Nakazawa, Yusuke (1340) | Won 2-0 | +151512 |
| 6standard | 685 | Harada, Dampei (1714) | Won 2-0 | +221534 |
| 7standard | 319 | Akiyama, Hiroki (1588) | Lost 0-2 | -171517 |
| 8standard | 826 | Sato, Tatsuo (1517) | Lost 1-2 | -181499 |
| top | average opponent: 1505record: 4-4 | new rating: 1499 | ||
| Grand Prix Nagoya 2016 (OGW limited) | starting rating: 1496 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 83 | Ozaki, Masaya (1435) | Won 2-0 | +171513 |
| 2sealed | 483 | Tamura, Ryo (1778) | Won 2-0 | +231536 |
| 3sealed | 166 | Itou, Hayato7608 (1658) | Lost 0-2 | -161520 |
| 4sealed | 803 | Honda, Jun'Ichi (1610) | Won 2-0 | +201540 |
| 5sealed | 413 | Matsuo, Keisuke (1513) | Lost 1-2 | -191521 |
| 6sealed | 397 | Irie, Shun (1478) | Lost 0-2 | -191502 |
| 7sealed | 809 | Sasaki, Shin (1418) | Won 2-0 | +171519 |
| 8sealed | 477 | Naitou, Hisashi (1506) | Lost 0-2 | -181501 |
| top | average opponent: 1550record: 4-4 | new rating: 1501 | ||
| Grand Prix Kobe 2015 (BFZ standard) | starting rating: 1483 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 229 | Sugiura, Hiroki (1536) | Lost 0-2 | -171466 |
| 2standard | 745 | Oosima, Keisuke (1482) | Lost 1-2 | -181448 |
| 3standard | 1106 | Saito, Naoki (1460) | Won 2-1 | +181466 |
| 4standard | 1046 | Nagamoto, Kouji (1483) | Won 2-1 | +181484 |
| 5standard | 918 | Hattori, Yutaka (1429) | Won 2-1 | +171501 |
| 6standard | 386 | Hirano, Aimi (1531) | Won 2-1 | +191520 |
| 7standard | 463 | Ito, Takuto (1475) | Won 2-1 | +171537 |
| 8standard | 194 | Kobayashi, Ukyo (1487) | Lost 0-2 | -191518 |
| 9standard | 317 | Nakasato, Hiroki (1292) | Lost 1-2 | -221496 |
| top | average opponent: 1464record: 5-4 | new rating: 1496 | ||
| Grand Prix Shizuoka 2015 (KTK limited) | starting rating: 1461 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 866 | Watanabe, Nobuyuki (1500) | Lost 1-2 | -171444 |
| 2sealed | 926 | Okumura, Yuji (1482) | Lost 1-2 | -181426 |
| 3sealed | 1112 | Honda, Yusuke (1463) | Lost 1-2 | -171409 |
| 4sealed | 1092 | Sekizawa, Tomohiko (1406) | Won 2-1 | +181427 |
| 5sealed | 1011 | Wada, Ippei (1398) | Won 2-0 | +171444 |
| 6sealed | 923 | Hosaka, Atsushi (1541) | Won 2-0 | +201464 |
| 7sealed | 859 | Ogata, Nobuhiko (1473) | Lost 1-2 | -181446 |
| 8sealed | 817 | Takamatsu, Hideyasu (1428) | Won 2-1 | +181464 |
| 9sealed | 764 | Tagaya, Makoto (1503) | Won 2-1 | +191483 |
| top | average opponent: 1466record: 5-4 | new rating: 1483 | ||
| Grand Prix Kobe 2014 (modern) | starting rating: 1454 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 288 | Enomoto, Masayuki (1443) | Lost 0-2 | -181436 |
| 2modern | 464 | Nomoto, Hidehiro (1426) | Won 2-0 | +181454 |
| 3modern | 324 | Kida, Yukihiro (1500) | Won 2-0 | +191473 |
| 4modern | 216 | Ueno, Takahiro (1503) | Won 2-1 | +181491 |
| 5modern | 127 | Arita, Kento (1673) | Lost 1-2 | -141477 |
| 6modern | 340 | Sakamoto, Ryousuke (1603) | Lost 1-2 | -161461 |
| top | average opponent: 1525record: 3-3 | new rating: 1461 | ||
| Grand Prix Nagoya 2014 (BNG limited) | starting rating: 1488 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 215 | Ichinose, Noritoshi (1500) | Won 2-0 | +181506 |
| 2sealed | 131 | Garcia, Marlon (1570) | Lost 0-2 | -171489 |
| 3sealed | 253 | Horie, Kazuo (1472) | Lost 0-2 | -181471 |
| 4sealed | 335 | Kamikawa, Yusuke (1482) | Won 2-0 | +181489 |
| 5sealed | 265 | Matsubara, Tohru (1556) | Lost 1-2 | -171472 |
| 6sealed | 298 | Yoshimura, Wataru (1483) | Lost 1-2 | -181454 |
| top | average opponent: 1511record: 2-4 | new rating: 1454 | ||
| Grand Prix Kitakyushu 2013 (M14 standard) | starting rating: 1496 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 136 | Hasegawa, Gaku (1606) | Lost 1-2 | -161480 |
| 2standard | 299 | Yoshida, Mitsutaka (1173) | Won 2-0 | +121492 |
| 3standard | 355 | Kusumoto, Masahiro (1407) | Lost 1-2 | -191473 |
| 4standard | 472 | Sudou, Erika (1368) | Won 2-0 | +161489 |
| 5standard | 406 | Lee, Wonchang (1496) | Won 2-1 | +181507 |
| 6standard | 365 | Kishimoto, Hiromichi (1432) | Lost 0-2 | -191488 |
| top | average opponent: 1414record: 3-3 | new rating: 1488 | ||
| Grand Prix Yokohama 2013 (GTC limited) | starting rating: 1514 | |||
| round | table | opponent (rating) | result | Δrating |
| 2sealed | 863 | Saijo, Youhei (1496) | Won 2-0 | +181532 |
| 3sealed | 734 | Iwasa, Shingo (1518) | Lost 0-2 | -181514 |
| 4sealed | 872 | Inoue, Masanao (1517) | Lost 1-2 | -181496 |
| top | average opponent: 1510record: 1-2 | new rating: 1496 | ||
| Grand Prix Nagoya 2012 (RTR standard) | starting rating: 1515 | |||
| round | table | opponent (rating) | result | Δrating |
| 2standard | 92 | Tada, Mitsuhiro (1500) | Won 2-0 | +171532 |
| 3standard | 5 | Nukushina, Shouta (1537) | Lost 0-2 | -181514 |
| 4standard | 508 | Fujimoto, Kousaku (1520) | Lost 0-2 | -181496 |
| 5standard | 515 | Wada, Akihiro (1432) | Won 2-0 | +171513 |
| 6standard | 398 | Sasaki, Tsutomu (1577) | Won 2-0 | +191532 |
| 7standard | 262 | Ishigaki, Ryouji (1519) | Lost 1-2 | -181514 |
| top | average opponent: 1514record: 3-3 | new rating: 1514 | ||
| Grand Prix Yokohama 2012 (modern) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 172 | Kobayashi, Yuuki (1500) | Won 2-1 | +181518 |
| 2modern | 252 | Ledesma, Mark (1518) | Won 2-0 | +181536 |
| 3modern | 92 | Ito, Shinichi (1533) | Lost 0-2 | -181518 |
| 4modern | 211 | Nishizawa, Taichi (1514) | Won 2-1 | +181536 |
| 5modern | 424 | Sasabe, Yusuke (1486) | Lost 0-2 | -191517 |
| 6modern | 398 | Hidaka, Ayumi (1589) | Lost 1-2 | -171500 |
| 7modern | 418 | Karikome, Hiroaki (1497) | Won 2-1 | +181518 |
| 8modern | 257 | Iwaide, Yoshitaka (1568) | Lost 1-2 | -171501 |
| 9modern | 263 | Ikeda, Naoto (1242) | Won 2-1 | +141515 |
| top | average opponent: 1494record: 5-4 | new rating: 1515 | ||