| Wing Co., Ltd | Tokyo |
| Wire and Wireless Co., Ltd | Tokyo |
| Wireless Tsukamoto Co., Ltd | Tokyo |
| Wisbrain | Tokyo |
| Wise Impact Co., Ltd | Hyogo |
| WISNET | Tokyo |
| WIT Lab | Tokyo |
| WIXI, Inc. | Tokyo |
| Wiz Corporation | Osaka |
| Wiz Software Corporation | Osaka |
| Wiz Tech Co., Ltd | Tokyo |
| WiZaaS Co., Ltd | Tokyo |
| Wizard | Tokyo |
| Wizard System Laboratory Co,. Ltd | Tokyo |
| Wizcorp, Inc. | |
| Work Style Tech Co., Ltd | Tokyo |
| Worker Bee Co., Ltd | Tokyo |
| Works Applications Co., Ltd | Tokyo |
| World Design Co., Ltd | Aichi |
| Worldsoft | Tokyo |
| Woven by Toyota, Inc. | Tokyo |
| Wovn Technologies, Inc. | |
| WOWOW Communications, Inc. | Kanagawa |
| WQC Co., Ltd | Tokyo |
| WRI Solution Co., Ltd | Tokyo |
| Wunder Transport Technologies Co., Ltd | Tokyo |
| Wunderbar | |
| WWS Corporation | Osaka |
| X Garden Co., Ltd | Tokyo |
| X Mile Co., Ltd | Tokyo |
| X-Hub Tokyo | Tokyo |
| X-Knowledge Co., Ltd | Tokyo |
| X-mov Japan Co., Ltd | Hyogo |
| Xebec Co., Ltd | Osaka |
| Xebec Japan Co., Ltd | Tokyo |
| Xenodata Lab Co., Ltd | Tokyo |
| xFOREST Therapeutics Co., Ltd | |
| xID Co., Ltd | Tokyo |
| Xilisoft Corporation | Tokyo |
| Xincor miXell Co., Ltd | Tokyo |
| XincX, LLC | Tokyo |
| Xing Co., Ltd | Aichi |
| XMart Co., Ltd | Tokyo |
| XML Consortium Community | Tokyo |
| XML Master | Tokyo |
| Xoops | Tokyo |
| XOOPS Cube | Tokyo |
| XREA | Osaka |
| Xserver, Inc. | Kyoto |
| XTech Corporation | Tokyo |