| # | Name | Location | Applications |
|---|---|---|---|
| 1. | DKK Co., Ltd. | 🇯🇵 , Japan | 1 |
| 2. | DKK Company, Limited | 🇯🇵 Tokyo, Japan | 2 |
| 3. | DKK Company, Limited | 🇯🇵 Chiyoda-ku, Tokyo, Japan | 4 |
| 4. | DKK Corporation | 🇯🇵 Tokyo, Japan | 1 |
| 5. | DKK Enterprises Inc. | 🇨🇦 Toronto, Canada | 1 |
| 6. | DKK-TOA Corporation | 🇯🇵 Tokyo, Japan | 4 |
| 7. | DKK-TOA Yamagata Corporation | 🇯🇵 Shinjo-shi, Japan | 1 |