| Daido Engineering Corporation | |
| Daido University | |
| DaidoSystem Co., Ltd | Ishikawa |
| Daifuku Co., Ltd | Osaka |
| Daiichi Institute of Technology | |
| Daiichi Keisan Center, Inc. | Tokyo |
| Daiichi University of Pharmacy | |
| Daikoku Denki Co., Ltd | Aichi |
| Dainichi Electronics Co., Ltd | Kanagawa |
| Dainichi Shoji Co., Ltd | Tokyo |
| Daishinku Corporation | Hyogo |
| Daitec Co., Ltd | Tokyo |
| Daito Bunka University | |
| Daitron Electron Co., Ltd | Osaka |
| Daiwa Corporate Investment Co., Ltd | Tokyo |
| Daiwa Securities Group, Inc. | |
| Daiwabo Information System Co., Ltd | Tokyo |
| Dandelion Co., Ltd | Saitama |
| DangoNet Co., Ltd | Tokyo |
| DanRegister | Osaka |
| DATA Business Co., Ltd | Tokyo |
| Data Chemistry Co., Ltd | Tokyo |
| Data Design Co., Ltd | Tokyo |
| Data Index Corporation | Tokyo |
| Data Salvage | Tokyo |
| Data Science Professionals Co., Ltd | Tokyo |
| Data Scope Co., Ltd | Tokyo |
| Data Section Co., Ltd | Tokyo |
| Data Vehicle, Inc. | |
| Data Viz Lab Co., Ltd | Tokyo |
| Datachain Co., Ltd | Tokyo |
| DataCook Co., Ltd | Tokyo |
| DataFluct, Inc. | |
| DataLive Corporation | Tokyo |
| Datamix Co., Ltd | Tokyo |
| Dataseed, Inc. | |
| DataSign Co., Ltd | Tokyo |
| DATATrak Co., Ltd | Tokyo |
| Datawave Co., Ltd | Nagasaki |
| dataX, Inc. | |
| Datum Studio Co., Ltd | Tokyo |
| DayBridge Co., Ltd | Tokyo |
| DBJ Capital Co., Ltd | Tokyo |
| DCN Internet Service | Tokyo |
| DDS Co., Ltd | Aichi |
| Debian JP Project | Tokyo |
| Decsys Corporation | Chiba |
| DeepCore Co., Ltd | Tokyo |
| Delight Co., Ltd | Tokyo |
| Delight Corporation | Tokyo |