| Yusen Logistics Co., Ltd | Tokyo |
| Yutaka Electric Manufacturing Co., Ltd | Tokyo |
| Yuto Hands Co., Ltd | Tokyo |
| YZ Co., Ltd | Tokyo |
| Z Corporation Co., Ltd | Tokyo |
| Z Venture Capital Corporation | Tokyo |
| Zaikei - IT-Science | Tokyo |
| Zanden Audio Systems | Osaka |
| Zappa Co., Ltd | Tokyo |
| ZAQ | Tokyo |
| ZeGraph | Osaka |
| Zeku Corporation | Tokyo |
| Zelas Co., Ltd | Tokyo |
| Zen-Cart | Tokyo |
| ZENET Co., Ltd | Tokyo |
| Zenis Co., Ltd | Tokyo |
| Zephyr Systems Co., Ltd | Tokyo |
| ZERIA Pharmaceutical Co., Ltd | Tokyo |
| Zero Internet Provider | Tokyo |
| Zero-Ten Co., Ltd | Fukuoka |
| Zerobillbank Japan, Inc. | Tokyo |
| Zeroboard, Inc. | |
| ZeroCAD | Osaka |
| Zerosoft Co., Ltd | Tokyo |
| Zest Co., Ltd | Tokyo |
| Zestec Co., Ltd | Tokyo |
| Zionex Co., Ltd | Tokyo |
| ZMP Co., Ltd | Tokyo |
| ZMP, Inc. | Tokyo |
| Zo Digital Japan | |
| ZOA Corporation | Tokyo |
| Zokei Co., Ltd | Tokyo |
| Zooog Co., Ltd | Tokyo |
| ZTV Co., Ltd | Mie |
| ZubaTech Co., Ltd | Tokyo |
| Zucks Co., Ltd | Tokyo |
| Zuken, Inc. | Kanagawa |
| Zukosha | Hokkaido |
| Zumensoft | Tokyo |
| Zynas Co., Ltd | Tokyo |