Keio Challenger
      
The Keio Challenger is a professional tennis tournament played on hard courts. It is currently part of the Association of Tennis Professionals (ATP) Challenger Tour. It is held annually in Yokohama, Japan, since 1999 (but tournament didn't exist in years 2003–2006).
Past finals
Singles
| Year | Champion | Runner-up | Score | 
| 2014 |  John Millman |  Kyle Edmund | 6–4, 6–4 | 
| 2013 |  Matthew Ebden |  Go Soeda | 2–6, 7–6(7–3), 6–3 | 
| 2012 |  Matteo Viola |  Mirza Bašić | 7–6(7–3), 6–3 | 
| 2011 | Not Held | 
| 2010 | Not Held | 
| 2009 |  Takao Suzuki |  Martin Fischer | 6–4, 7–6(5) | 
| 2008 |  Lee Hyung-taik |  Go Soeda | 7–5, 6–3 | 
| 2007 |  Dudi Sela |  Takao Suzuki | 6–7(5), 6–4, 6–2 | 
| 2006 -
 2003
 | Not Held | 
| 2002 |  Lee Hyung-taik |  John van Lottum | 2–6, 7–6(2), 7–6(6) | 
| 2001 |  Takao Suzuki |  Gouichi Motomura | 6–2, 6–7(5), 7–6(4) | 
| 2000 |  Eric Taino |  Julian Knowle | 7–6(5), 6–4 | 
| 1999 |  Lee Hyung-taik |  Paradorn Srichaphan | 6–3, 6–0 | 
Doubles
| Year | Champions | Runners-up | Score | 
| 2014 |  Bradley Klahn 
  Matt Reid |  Marcus Daniell 
  Artem Sitak | 4–6, 6–4, [10–7] | 
| 2013 |  Bradley Klahn 
  Michael Venus |  Sanchai Ratiwatana 
  Sonchat Ratiwatana | 7–5, 6–1 | 
|
| 2012 |  Prakash Amritraj 
  Philipp Oswald |  Sanchai Ratiwatana 
  Sonchat Ratiwatana | 6–3, 6–4 | 
| 2011 | Not Held | 
| 2010 | Not Held | 
| 2009 |  Yang Tsung-hua 
  Yi Chu-huan |  Alexey Kedryuk 
  Junn Mitsuhashi | 6–7(9), 6–3, [12–10] | 
| 2008 |  Tomáš Cakl 
  Marek Semjan |  Brendan Evans 
  Martin Slanar | 6–3, 7–6(1) | 
| 2007 |  Hiroki Kondo 
  Go Soeda |  Satoshi Iwabuchi 
  Toshihide Matsui | 6–7(5), 6–3, [11–9] | 
| 2006 -
 2003
 | Not Held | 
| 2002 |  Lu Yen-hsun 
  Danai Udomchoke |  Ivo Karlović 
  Mark Nielsen | 7–6(5), 6–3 | 
| 2001 |  Takao Suzuki 
  Mitsuru Takada |  Marco Chiudinelli 
  Sebastian Jäger | 6–3, 6–4 | 
| 2000 |  Yves Allegro 
  Julian Knowle |  Tim Crichton 
  Ashley Fisher | 6–3, 7–6(2) | 
| 1999 |  Satoshi Iwabuchi 
  Thomas Shimada |  Michael Joyce 
  Kyle Spencer | 6–2, 6–4 | 
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