| Teikyo University | |
| TEIKYO University of Science | Tokyo |
| Teikyo-Gakuen Junior College | |
| TEKHNE Corporation | Kanagawa |
| Tekoma Energy K.K. | |
| Tekwind Co., Ltd | Tokyo |
| Tele-net Corporation | Tokyo |
| Telecom Engneering Center | Tokyo |
| Telecom Services Association | Tokyo |
| Telecomedia Co., Ltd | Tokyo |
| Telecommunications Carriers Association | Tokyo |
| Telecommunications Technology Committee | Tokyo |
| Telephone Agency Service Co., Ltd | Tokyo |
| Telexistence Co., Ltd | Tokyo |
| Temple University, Japan Campus | |
| Tenchijin, Inc. | |
| Tenri University | |
| Tensei Data Net Co., Ltd | Fukui |
| Tenshi College | |
| TEPCO Optical Network Engineering Co., Ltd | Tokyo |
| Tera, Inc. | Tokyo |
| Terada Electric Works Co., Ltd | Tokyo |
| Terra | Tokyo |
| Terra Space Co., Ltd | Kyoto |
| Terrabyte Co., Ltd | Tokyo |
| TerraSky Ventures Co., Ltd | |
| TESEC Corporation | Tokyo |
| Tezukayama Gakuin University | |
| Tezukayama University | |
| TFK Co., Ltd | Hyogo |
| TG Solutions Corporation | Tokyo |
| THA Ltd | |
| The Bridge Co., Ltd | Tokyo |
| The FSI Network | Tokyo |
| The Noguchi Institute | |
| The Plant Co., Ltd | Tokyo |
| THine Electronics, Inc. | Tokyo |
| Think IT | Tokyo |
| ThinkethBank Co., Ltd | Tokyo |
| Thirdverse Co., Ltd | Tokyo |
| Thirdverse, Co., Ltd | |
| THS Co., Ltd | Tokyo |
| Tier IV Co., Ltd | Tokyo |
| Tiida Net Company Co., Ltd | Okinawa |
| TikiTiki Internet | Tokyo |
| TimeTechnologies Ltd | Tokyo |
| TIS Intec Group | Tokyo |
| TIS Solution Link Co., Ltd | Tokyo |
| TMCreation | |
| TMH Co., Ltd | Oita |