2023 Keio Challenger – Men's singles
| Men's singles | |
|---|---|
| 2023 Keio Challenger | |
| Champion | Yosuke Watanuki |
| Runner-up | Yuta Shimizu |
| Score | 7–6(7–5), 6–4 |
Christopher O'Connell was the defending champion but chose not to defend his title.
Yosuke Watanuki won the title after defeating Yuta Shimizu 7–6(7–5), 6–4 in the final.