| To Solutions Co., Ltd | Tokyo |
| To-Conne Co., Ltd | Tokyo |
| TOA Corporation | Tokyo |
| Toggle Holdings, Inc. | |
| Tohichi Kyosan Cable Ltd | Tokyo |
| Toho Densen Kogyo Co., Ltd | Tokyo |
| Toho System Science Co., Ltd | Tokyo |
| Toho University | |
| Tohoku Bunka Gakuen University | |
| Tohoku Bunkyo College | |
| Tohoku Fukushi University | |
| Tohoku Gakuin University | Miyagi |
| Tohoku Institute of Technology | Miyagi |
| Tohoku Medical and Pharmaceutical University | |
| Tohoku University | Miyagi |
| Tohoku University - Division of Mathematics | Miyagi |
| Tohoku University - Graduate School of Information Sciences | |
| Tohoku University - Mathematical Institute | |
| Tohoku University of Art & Design | |
| Tohoku University of Community Service and Science | |
| Tohto University | |
| Toin Gakuen | |
| Toita Women's College | |
| Tokai Automation Co., Ltd | Aichi |
| TOKAI Communications Corporation | Tokyo |
| Tokai Gakuin University | |
| Tokai Semitsu Kogyo Co., Ltd | Tokyo |
| Tokai University | |
| Tokaigakuen University | |
| TOKI Commercial Co., Ltd | |
| Tokione Planning Co., Ltd | Tokyo |
| TOKIUM, Inc. | |
| Tokiwa University | |
| Tokiwa-Bio, Inc. | |
| Tokoha University | |
| Tokoro Channel LPC | Saitama |
| Tokushima Bunri Uuniversity | |
| Tokushima College of Technology | |
| Tokushima University | |
| Tokyo Artisan Intelligence | |
| Tokyo Christian University | |
| Tokyo City University | |
| Tokyo Computer Service Co., Ltd | Tokyo |
| Tokyo Denki University | |
| TOKYO DENSEI Industrial Co., Ltd | |
| Tokyo Drawing Ltd | |
| Tokyo Electron Device Ltd | Kanagawa |
| Tokyo FinTech | Tokyo |
| Tokyo Fluid Research | |
| Tokyo Fuji University | |