| BusinessRalliart, Inc. | Tokyo |
| Butsuryo College of Osaka | |
| Buzzreach Co., Ltd | Tokyo |
| byus&co. Co., Ltd | |
| C&A Solution Co., Ltd | Ibaraki |
| C.CUBE, Inc. | Tokyo |
| C2D2 Co., Ltd | Aichi |
| CAB Co., Ltd | Tokyo |
| Cable Media Waiwai Co., Ltd | Tokyo |
| CAC Corporation | Tokyo |
| CAC-K | Tochigi |
| Cactus Communications Co., Ltd | Tokyo |
| CAM, Inc. | Tokyo |
| Camelot Software Planning Co., Ltd | Tokyo |
| Canal Ventures Co., Ltd | |
| CanBas Co., Ltd | Shizuoka |
| Canon ANELVA Corporation | Kanagawa |
| Canon Electronics, Inc. | Saitama |
| Canon IT Solutions, Inc. | Tokyo |
| Canon Marketing Japan Co., Ltd | Tokyo |
| Canon Medical Systems Corporation | Tochigi |
| Canon, Inc. | Tokyo |
| Canow Co., Ltd | |
| Cansystem Co., Ltd | Tokyo |
| CAPA, Inc. | Tokyo |
| Capcom Co., Ltd | Tokyo |
| Career Bijin Consulting Co., Ltd | Tokyo |
| Career Systems Co., Ltd | Tokyo |
| Carl Systems Co., Ltd | Tokyo |
| Carlin Co., Ltd | Tokyo |
| Carna Biosciences Co., Ltd | Hyogo |
| Carpe Noctem K.K. | |
| CarrotSoftware Co., Ltd | Tokyo |
| Carta Ventures Co., Ltd | Tokyo |
| Casio Computer Co., Ltd | Tokyo |
| Casio Techno Co., Ltd | Tokyo |
| CastingRoad Co., Ltd | Tokyo |
| Catalogue Consultant Co., Ltd | Tokyo |
| Catalyst System Co., Ltd | Tokyo |
| Catana Corporation | Shizuoka |
| Catchball21 Co., Ltd | Tokyo |
| CBcloud Co., Ltd | Tokyo |
| CEATEC Japan | Tokyo |
| Cedars Communications Co., Ltd | Hokkaido |
| Ceek.jp | Tokyo |
| Celaid Therapeutics | |
| Cellbank Co., Ltd | Tokyo |
| CellGenTech, Inc. | |
| CellSeed Co., Ltd | Tokyo |
| Cellusion Co., Ltd | Tokyo |