| DigitalMaker Co., Ltd | Saitama |
| Digitalstage Co., Ltd | Tokyo |
| Digitalstage, Inc. | Tokyo |
| Dioseve, Inc. | |
| DiproTech Co., Ltd | |
| Direct Search Japan Co., Ltd | Tokyo |
| DirectCloud Co., Ltd | Tokyo |
| Distributors Association of Foreign Semiconductors | Tokyo |
| Divic Corporation | Kanagawa |
| DLE Capital Co., Ltd | Tokyo |
| DMC Co., Ltd | Tokyo |
| DMM Games Ventures | |
| Do-Reg | Tokyo |
| Do-To Com Domain Service | Osaka |
| DOCOMO Technology Co., Ltd | Tokyo |
| Doctor-NET Co., Ltd | Tokyo |
| Doctorsoft Co., Ltd | Kanagawa |
| Doho University | |
| Dojindo Laboratories Co., Ltd | Kumamoto |
| DokiDoki | Tokyo |
| Dokidoki Groove Works Co., Ltd | Tokyo |
| Dokkyo Medical University | |
| Dokkyo University | |
| Dolphin Software | Tokyo |
| Dolphy Software | Tokyo |
| DomainService | Tokyo |
| Doorkeeper | |
| Doshin Medic Co., Ltd | Tokyo |
| Doshisha University | |
| Doshisha Women's College of Liberal Arts | |
| Dospora Computer Shop | Tokyo |
| DOT World Co., Ltd | Tokyo |
| DOT World, Inc. | |
| Double Jump.tokyo Co., Ltd | Tokyo |
| Double Sharp Partners Corporation | Tokyo |
| DOWA Electronics Materials Co., Ltd | Tokyo |
| Dragon Network Corporation | Tokyo |
| Dream Incubator Co., Ltd | Tokyo |
| Dream Train Internet, Inc. | Tokyo |
| Dreamware Shizuoka Co., Ltd | Tokyo |
| Drive Network | Tokyo |
| Drone Fund | Tokyo |
| Drone Games Co., Ltd | Tokyo |
| Drupal Japan | Tokyo |
| DS Solution, Inc. | |
| DS Technologies Co., Ltd | Tokyo |
| DSI Co., Ltd | Tokyo |
| DSR Co., Ltd | Tokyo |
| DTS Corporation | Tokyo |
| DTS Insight Corporation | |