# 2017 Keio Challenger – Men's singles

Taro Daniel was the defending champion but chose not to defend his title.
Yūichi Sugita won the title after defeating Kwon Soon-woo 6–4, 2–6, 7–6$^{(7–2)}$ in the final.

## Seeds

* Yūichi Sugita (champion)
* Henri Laaksonen (first round)
* Lee Duck-hee (first round)
* Go Soeda (second round)
* Grega Žemlja (first round)
* Ruben Bemelmans (second round)
* Zhang Ze (quarterfinals)
* Andrew Whittington (quarterfinals)

## 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 | Final |
| 1 | Yūichi Sugita | 4 | 7$^8$ | 6 | | | | | |
| Q | Blake Mott | 6 | 6$^6$ | 2 | | | | | |
| Q | Blake Mott | 6 | 6$^6$ | 2 | 1 | Yūichi Sugita | 6 | 2 | 7$^7$ |
| | | | | | Q | Kwon Soon-woo | 4 | 6 | 6$^2$ |
| | Tatsuma Ito | 4 | 4 | | Q | Kwon Soon-woo | 4 | 6 | 6$^2$ |
| Q | Kwon Soon-woo | 6 | 6 | | | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | Y Sugita | 6 | 6 | | | | | | | | | | | | | | |
| | A Velotti | 4 | 4 | | 1 | Y Sugita | 6 | 6 | | | | | | | | | |
| | C O'Connell | 1 | 7$^7$ | 3 | | D Wu | 4 | 4 | | | | | | | | | |
| | D Wu | 6 | 6$^1$ | 6 | | | | | 1 | Y Sugita | 6 | 6 | | | | | |
| | B Kavčič | 4 | 6 | 6 | | | | | 7 | Z Zhang | 2 | 1 | | | | | |
| | M Matosevic | 6 | 0 | 4 | | B Kavčič | 4 | 6$^5$ | | | | | | | | | |
| WC | Yo Watanuki | 3 | 0 | | 7 | Z Zhang | 6 | 7$^7$ | | | | | | | | | |
| 7 | Z Zhang | 6 | 6 | | | | | | | | | | 1 | Y Sugita | 4 | 7$^8$ | 6 |
| 3 | D-h Lee | 5 | 7$^8$ | 1 | | | | | | | | | Q | B Mott | 6 | 6$^6$ | 2 |
| | M Tepavac | 7 | 6$^6$ | 6 | | M Tepavac | 3 | 4 | | | | | | | | | |
| | F Škugor | 3 | 5 | | Q | B Klein | 6 | 6 | | | | | | | | | |
| Q | B Klein | 6 | 7 | | | | | | Q | B Klein | 4 | 1 | | | | | |
| | M Polmans | 4 | 7 | 6 | | | | | Q | B Mott | 6 | 6 | | | | | |
| PR | C-M Stebe | 6 | 5 | 0 | | M Polmans | 4 | 2 | | | | | | | | | |
| Q | B Mott | 6 | 6 | | Q | B Mott | 6 | 6 | | | | | | | | | |
| 5 | G Žemlja | 2 | 3 | | | | | | | | | | | | | | |

### 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 | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 6 | R Bemelmans | 6 | 6 | | | | | | | | | | | | | | | |
| SE | L Harris | 3 | 4 | | 6 | R Bemelmans | 4 | 6 | 3 | | | | | | | | | |
| | Y Uchiyama | 4 | 6 | 3 | WC | K Uesugi | 6 | 3 | 6 | | | | | | | | | |
| WC | K Uesugi | 6 | 1 | 6 | | | | | | WC | K Uesugi | 7$^7$ | 2 | 6$^2$ | | | | |
| | J De Loore | 6$^3$ | 1 | | | | | | | | T Ito | 6$^3$ | 6 | 7$^7$ | | | | |
| | T Ito | 7$^7$ | 6 | | | T Ito | 6 | 6 | | | | | | | | | | |
| | H Moriya | 4 | 4 | | 4 | G Soeda | 4 | 1 | | | | | | | | | | |
| 4 | G Soeda | 6 | 6 | | | | | | | | | | | | | T Ito | 4 | 4 |
| 8 | A Whittington | 6$^5$ | 6 | 6 | | | | | | | | | | | Q | S-w Kwon | 6 | 6 |
| WC | Sora Fukuda | 7$^7$ | 4 | 2 | 8 | A Whittington | 6 | 7$^7$ | | | | | | | | | | |
| Q | T Niki | 6 | 6 | | Q | T Niki | 4 | 6$^5$ | | | | | | | | | | |
| WC | Masato Shiga | 1 | 1 | | | | | | | 8 | A Whittington | 4 | 4 | | | | | |
| Q | S-w Kwon | 6 | 7$^7$ | | | | | | | Q | S-w Kwon | 6 | 6 | | | | | |
| | J Jung | 3 | 6$^2$ | | Q | S-w Kwon | 7$^7$ | 6 | | | | | | | | | | |
| | Z Li | 6 | 7$^7$ | | | Z Li | 6$^5$ | 3 | | | | | | | | | | |
| 2 | H Laaksonen | 3 | 6$^5$ | | | | | | | | | | | | | | | |