| Date: | 16 November – 22 November |
| Edition: | 11th |
| Surface: | Hard |
| Location: | Yokohama, Japan |
| Champs: |  Taro Daniel |
| Champd: |  Sanchai Ratiwatana / Sonchat Ratiwatana |
| After Year: | 2017 |
The 2015 Keio Challenger is a professional tennis tournament played on hard courts. It is the eleventh edition of the tournament which is part of the 2015 ATP Challenger Tour. It takes place in Yokohama, Japan between November 16 and November 22, 2015.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Australia | John Millman | 91 | 1 | |
| Australia | Matthew Ebden | 107 | 2 | |
| Japan | Tatsuma Ito | 113 | 3 | |
| Japan | Go Soeda | 115 | 4 | |
| Japan | Taro Daniel | 119 | 5 | |
| Japan | Yūichi Sugita | 123 | 6 | |
 Russian Federation | Konstantin Kravchuk | 145 | 7 | |
| Japan | Yoshihito Nishioka | 146 | 8 |
The following players received wildcards into the singles main draw:
Sora Fukuda Makoto Ochi Masato Shiga Kaito UesugiThe following players received entry from the qualifying draw:
Yusuke Watanuki Kento Takeuchi Yuya Kibi
Peter KobeltSee main article: 2015 Keio Challenger – Singles.
Taro Daniel def. Go Soeda 4–6, 6–3, 6–3See main article: 2015 Keio Challenger – Doubles.
Sanchai Ratiwatana / Sonchat Ratiwatana def. 
Riccardo Ghedin / Yi Chu-huan 6–4, 6–4