Ground: Hardcourt outdoor
| ITF Guam F1 | 2015/05/25 01:00 | Katsuki Nagao v Olly Sadler | 6-4,6-4 |
| ITF Thailand F9 | 2015/04/25 04:00 | Katsuki Nagao v Zach Itzstein | 5-7,3-6 |
| ITF Thailand F9 | 2015/04/20 04:00 | Katsuki Nagao v Shunrou Takeshima | 4-6,5-7 |
| ITF Thailand F9 | 2015/04/19 03:00 | Katsuki Nagao v Sonchat Ratiwatana | 6-3,6-3 |
| ITF Thailand F9 | 2015/04/18 04:00 | Katsuki Nagao v Jatuporn Nalamphun | 6-0,6-2 |
| ITF Japan F3 | 2015/03/22 01:00 | Yuki Nakamura v Katsuki Nagao | 7-6,6-0 |
| ITF Japan F2 | 2015/03/18 02:55 | Duckhee Lee v Katsuki Nagao | 6-3,7-5 |
| ITF Japan F2 | 2015/03/16 01:00 | Chih-Jen Ho v Katsuki Nagao | 4-6,4-6 |
| ITF Guam F1 | 2014/05/27 00:00 | Brendan Moore v Atsushi Ushida | 7-5,0-6,5-7 |