| Surugadai University | |
| Surv BioPharma, Inc. | |
| SUS Corporation | |
| Sustainable Lab, Inc. | |
| Susumu Co., Ltd | Kyoto |
| Suzuka University / Suzuka Junior College | |
| Suzuka University of Medical Science | |
| Suzuki Educational Software Co., Ltd | Shizuoka |
| SWCC Corporation | |
| Switch Co., Ltd | Okayama |
| Sycom Co., Ltd | Tokyo |
| Symphony, Inc. | Tokyo |
| Synapse Co., Ltd | Tokyo |
| SYNC Information System Co., Ltd | Osaka |
| Synergy Marketing, Inc. | Tokyo |
| Synergy-Systems Co., Ltd | Tokyo |
| Synplogen Co., Ltd | |
| Synspective | Tokyo |
| Syntec Ventures, Inc. | |
| Sysamic K.K. | |
| Sysazzle, Inc. | |
| Sysbank | Tokyo |
| Sysmex Corporation | Hyogo |
| SYSTEC Corporation | |
| System AI Co., Ltd | Tokyo |
| System Coordinate Co., Ltd | Tokyo |
| System Development Laboratory Co., Ltd | Osaka |
| System Infinity Co., Ltd | Tokyo |
| System Integrator Corporation | Tokyo |
| System Quest | Osaka |
| System Sekkei, Inc. | |
| System Works Corporation | Tokyo |
| SYSTEM-I, Inc. | Osaka |
| SYSTEMAX Co., Ltd | Tokyo |
| Systemlab Corporation | Tokyo |
| SystemLSI Co., Ltd | Ehime |
| Systems Service Co., Ltd | Tokyo |
| systemsGo | Tokyo |
| SystemSoft | Tokyo |
| SystemTalk, Inc. | Osaka |
| SystemV Co., Ltd | Tokyo |
| Systena Corporation | Tokyo |
| SYSystem Co., Ltd | Aichi |
| T Accelerator Co., Ltd | Tokyo |
| T&D Information System Ltd | Tokyo |
| T&I Innovation Center Co., Ltd | Tokyo |
| T&S Co., Ltd | Kanagawa |
| T'sWare | Tokyo |
| T.D.I. Co., Ltd | Tokyo |
| T2, Inc. | |