Go Player Ratings

JAAbout ratings

Oya Koichi

Oya Koichi (大矢浩一) has a rating of 1510, ranked 257 of 452 in professional play. Their highest rating so far is 1863 (January 17, 2013).

Oya Koichi9 dan大矢浩一Nihon Ki-in Tokyo
Rating1510
Rank257
1-year change↑7
Peak rating1863
Last 10312-292
2026 record
4-8
Record since 1927
312-292
Win rate
.517

The rating is calculated from published game results. It does not include any adjustment for playing Black.

Professional ratingsFind a player

Rating history — professional

14 gamesHigh 1537Low 1509
46 gamesHigh 1627Low 1504
93 gamesHigh 1671Low 1504
345 gamesHigh 1863Low 1504

The “All” view starts at 2006; earlier years are used only to warm up the calculation and are not shown.

Recent games

Up to 20 games, newest first. “Change” is the rating movement.
DateOpponent and tournamentResultChange
August 3, 2026Ko IunSGW Cup Chuyo Preliminary Semifinal　Colors unknown↓18
August 3, 2026Nakajima MiekoSGW Cup Chuyo Preliminary Round 1　Colors unknown↑7
July 9, 2026Seki KotaroMeijin　Colors unknown↓1
June 8, 2026Ko ReibunOza　Colors unknown↓12
June 1, 2026Suzuki ShinjiHoninbo　Colors unknown↓2
April 23, 2026Nobuta ShigehitoHoninbo　Colors unknown↑3
April 13, 2026Ohashi HirofumiMeijin　Colors unknown↑26
April 6, 2026Jo BunenGosei　Colors unknown↓12
March 30, 2026Toyoda HirohitoTengen　Colors unknown↓11
March 12, 2026Kubo HideoMeijin　Colors unknown↑19
February 12, 2026Jo BunenJudan Preliminary C　as Black↓14
January 15, 2026Chang FukangKisei First Tournament Preliminary Round 1　Colors unknown↓6
December 18, 2025Hino ShotaMeijin　Colors unknown↑19
November 20, 2025Shimosaka MioriMeijin　Colors unknown↑11
August 18, 2025Izawa AkinoSGW Cup Chuyo Preliminary Round 1　as Black↓24
August 7, 2025Awaji ShuzoOza　Colors unknown↓13
July 31, 2025Chen BoshaoTengen　Colors unknown↓14
July 7, 2025Kono YukioRyusei　Colors unknown↑2
July 7, 2025Mimura TomoyasuRyusei　Colors unknown↓6
May 22, 2025Sonoda YasutakaOza　Colors unknown↑19

Head-to-head

Up to 10 opponents, most-played first. Records are from Oya Koichi's point of view; jigo and no-result games are not counted as wins or losses. Only games from 1927 onward are included.
OpponentTotalAs BlackAs White
Kataoka Satoshi5-6.4552-22-2
Yoda Norimoto4-6.4002-51-1
Cho Sonjin1-9.1001-30-3
Ishida Yoshio3-6.3332-31-1
Ryu Shikun3-5.3752-11-2
Awaji Shuzo2-5.2860-10-0
O Rissei0-7.0000-30-3
Okada Shinichiro5-2.7141-01-0
Mizokami Tomochika2-5.2861-10-0
Yuki Satoshi1-6.1431-20-4
Mimura Tomoyasu1-5.1670-01-2
Aoki Shinichi4-2.6670-11-0
So Yokoku1-5.1670-10-1
Rin Kaiho3-3.5000-22-0
Yamada Kimio4-2.6672-12-1
Komatsu Hideki3-3.5000-01-1
Cho Chikun1-5.1671-30-2
Nakaonoda Tomomi1-5.1670-11-0
Michael Redmond5-1.8331-02-0
Kato Masao1-4.2001-20-2
Takemiya Masaki3-2.6001-12-0
Shuto Shun2-3.4000-01-0
Takao Shinji0-5.0000-30-1
Ishikura Noboru3-2.6001-11-0
Kobayashi Satoru2-3.4001-01-3
Nakamura Hidehito3-2.6001-10-0
Otake Hideo3-2.6002-11-1
Kono Rin3-2.6001-00-1

Record by year

Counted by calendar year, January to December (default wins and losses are included; jigo and no-result games are not). Only games from 1927 onward are counted, so these totals do not match the career records published by the two Ki-in.

YearRecordWin rate
20264-8.333
20256-10.375
20248-8.500
202314-12.538
20226-10.375
202111-10.524
202013-9.591
201914-11.560
20189-12.429
201713-14.481
201611-10.524
201517-10.630
20146-5.545
20135-8.385
201217-8.680
201110-10.500
20103-2.600
20093-3.500
20081-4.200
20070-2.000
20066-10.375
200514-14.500
200416-8.667
200312-11.522
200218-7.720
20011-4.200
20002-4.333
19991-3.250
19986-3.667
19972-4.333
19962-01.000
19950-5.000
19947-5.583
199310-8.556
19927-7.500
19917-7.500
19905-5.500
19892-4.333
19883-5.375
198710-5.667
19865-6.455
19855-1.833
Total312-292.517

Calculated from games played between 1927 and 2026 (as of September 17, 2026).