Ground: Hardcourt outdoor
| ITF Guam F1 | 2015/05/25 01:00 | Nagao, Katsuki v Sadler, Olly | 6-4,6-4 |
| ITF Thailand F9 | 2015/04/25 04:00 | Nagao, Katsuki v Itzstein, Zach | 5-7,3-6 |
| ITF Thailand F9 | 2015/04/20 04:00 | Nagao, Katsuki v 타케시마, 순로우 | 4-6,5-7 |
| ITF Thailand F9 | 2015/04/19 03:00 | Nagao, Katsuki v 라티와타나, 손채트 | 6-3,6-3 |
| ITF Thailand F9 | 2015/04/18 04:00 | Nagao, Katsuki v Nalamphun, Jatuporn | 6-0,6-2 |
| ITF Japan F3 | 2015/03/22 01:00 | Nakamura, Yuki v Nagao, Katsuki | 7-6,6-0 |
| ITF Japan F2 | 2015/03/18 02:55 | 이, 덕희 v Nagao, Katsuki | 6-3,7-5 |
| ITF Japan F2 | 2015/03/16 01:00 | Ho, Chih-Jen v Nagao, Katsuki | 4-6,4-6 |
| ITF Guam F1 | 2014/05/27 00:00 | Moore, B. v Ushida, Atsushi | 7-5,0-6,5-7 |