| Chubu Electric Power Co., Inc. | Shikoku Electric Power Co. |
| Chugoku Electric Power Co. | The Japan Atomic Power Company |
| E.P.D.C. | The Kansai Electric Power Co. |
| Hokkaido Electric Power Co. | The Okinawa Electric Power Co., Inc. |
| Hokuriku Electric Power Co. | The Tokyo Electric Power Co. |
| Kyushu Electric Power Co., Inc. | Toho Gas Co., Ltd. |
| Osaka Gas Co., Ltd. | Tohoku Electric Power Co. |
| Saibu Gas Co., Ltd. |
Tokyo Gas Co., Ltd. |