# 2004 AIG Japan Open Tennis Championships – Women's singles

Maria Sharapova was the defending champion and successfully defender her title, by defeating Mashona Washington 6–0, 6–1 in the final.

## Seeds

The first two seeds received a bye into the second round.
* Maria Sharapova (champion)
* Tatiana Golovin (second round)
* Shinobu Asagoe (first round)
* Kristina Brandi (second round)
* Meghann Shaughnessy (first round)
* Nicole Pratt (first round)
* Klára Koukalová (semifinals)
* Arantxa Parra Santonja (first round)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 1 | Maria Sharapova | 6 | 6 | | | | | |
| | Tamarine Tanasugarn | 2 | 3 | | | | | |
| | Tamarine Tanasugarn | 2 | 3 | | 1 | Maria Sharapova | 6 | 6 |
| | | | | | | Mashona Washington | 0 | 1 |
| | Mashona Washington | 3 | 7 | 6 | | Mashona Washington | 0 | 1 |
| 7 | Klára Koukalová | 6 | 5 | 2 | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| | | | | | 1 | M Sharapova | 6 | 1 | 6 | | | | | | | | |
| | A Nakamura | 3 | 5 | | Q | S Stosur | 4 | 6 | 3 | | | | | | | | |
| Q | S Stosur | 6 | 7 | | | | | | | 1 | M Sharapova | 6 | 6 | | | | |
| | K Srebotnik | 5 | 0 | | | | | | | Q | Y Fedossova | 3 | 4 | | | | |
| | A Morigami | 7 | 6 | | | A Morigami | 3 | 6$^7$ | | | | | | | | | |
| Q | Y Fedossova | 7 | 7$^7$ | | Q | Y Fedossova | 6 | 7$^9$ | | | | | | | | | |
| 5 | M Shaughnessy | 5 | 6$^5$ | | | | | | | | | | | 1 | M Sharapova | 6 | 6 |
| 3 | S Asagoe | 0 | 4 | | | | | | | | | | | | T Tanasugarn | 2 | 3 |
| | T Tanasugarn | 6 | 6 | | | T Tanasugarn | 6 | 7$^7$ | | | | | | | | | |
| | B Strýcová | 5 | 6 | 4 | | J Craybas | 3 | 6$^2$ | | | | | | | | | |
| | J Craybas | 7 | 4 | 6 | | | | | | | T Tanasugarn | 6 | 3 | | | | |
| Q | S Pe'er | 6 | 0 | 2 | | | | | | | A Kapros | 1 | 0$^r$ | | | | |
| | A Kapros | 2 | 6 | 6 | | A Kapros | 6 | 6 | | | | | | | | | |
| Q | S Karatantcheva | 6 | 6 | | Q | S Karatantcheva | 4 | 0 | | | | | | | | | |
| 8 | A Parra Santonja | 2 | 4 | | | | | | | | | | | | | | |

### Bottom half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 6 | N Pratt | 0 | 6 | 4 | | | | | | | | | | | | | | |
| | E Linetskaya | 6 | 1 | 6 | | E Linetskaya | 6 | 7 | | | | | | | | | | |
| WC | R Fujiwara | 6 | 6 | | WC | R Fujiwara | 4 | 5 | | | | | | | | | | |
| | S Obata | 4 | 4 | | | | | | | | E Linetskaya | 2 | 1 | | | | | |
| | M Sánchez Lorenzo | 2 | 4 | | | | | | | | M Washington | 6 | 6 | | | | | |
| | M Washington | 6 | 6 | | | M Washington | 6 | 6 | | | | | | | | | | |
| | S Kleinová | 6 | 3 | 4 | 4 | K Brandi | 2 | 2 | | | | | | | | | | |
| 4 | K Brandi | 4 | 6 | 6 | | | | | | | | | | | M Washington | 3 | 7 | 6 |
| 7 | K Koukalová | 6 | 6 | | | | | | | | | | | 7 | K Koukalová | 6 | 5 | 2 |
| | M Sequera | 2 | 2 | | 7 | K Koukalová | 6 | 6 | | | | | | | | | | |
| | Ľ Kurhajcová | 7$^7$ | 6 | | | Ľ Kurhajcová | 2 | 4 | | | | | | | | | | |
| | A Jidkova | 6$^5$ | 2 | | | | | | | 7 | K Koukalová | 6 | 6 | | | | | |
| | Y-j Cho | 3 | 4 | | | | | | | WC | N Vaidišová | 3 | 0 | | | | | |
| WC | N Vaidišová | 6 | 6 | | WC | N Vaidišová | 6 | 3 | 6 | | | | | | | | | |
| | | | | | 2 | T Golovin | 4 | 6 | 4 | | | | | | | | | |