| Precede Systems Co., Ltd | Tokyo |
| Precision System Science Co., Ltd | |
| Prefectural University of Hiroshima | |
| Prefectural University of Kumamoto | |
| Preferred Networks Co., Ltd | Tokyo |
| Prestige Corporation | Tokyo |
| Prima System Development Co., Ltd | Tokyo |
| Prime Gear Co., Ltd | Tokyo |
| primeNumber Co., Ltd | Tokyo |
| Primesoft | Tokyo |
| Print Net Co., Ltd | Kagoshima |
| Privatech Co., Ltd | Tokyo |
| Prometech Software Co., Ltd | Tokyo |
| Pronet Co., Ltd | Osaka |
| ProntoNet | Tokyo |
| Prosytem Corporation | Tokyo |
| Protec System Laboratory Co., Ltd. | |
| Protein Research Foundation | |
| Proto Co., Ltd | Tokyo |
| Prox System Design, Inc. | Tokyo |
| Psychic VR Lab Co., Ltd | Tokyo |
| Ptmind | Tokyo |
| PTS Co., Ltd | Tokyo |
| PuPuRu International | Tokyo |
| Pure Net | Tokyo |
| PuREC | |
| Purenic Japan | Tokyo |
| PURMX Therapeutics | |
| Python Japan User's Group | Tokyo |
| Q-Games Ltd | Kyoto |
| QBIT Robotics Corporation | Tokyo |
| Qiita Co., Ltd | Aichi |
| QUADRAC | |
| Qualitia Co., Ltd | Tokyo |
| QualitySoft Corporation | Tokyo |
| Quantum Leaps Capital Partners Corporation | |
| Quest Co., Ltd | Tokyo |
| Questfor | Tokyo |
| Quint Corporation | Tokyo |
| QunaSys Co., Ltd | Tokyo |
| R1SEO | |
| Radical Base | Tokyo |
| Radio NanoTherapeutics | |
| Radrix Co., Ltd | |
| Rain Interactive Co., Ltd | |
| Rainbow Japan, Inc. | Tokyo |
| Rakuno Gakuen University | |
| Rakuten Communications Corporation | Tokyo |
| Rakuten Infoseek | Tokyo |
| Rakuten Securities, Inc. | |