JUNO is a new submarine cable system connecting Japan and the United States, with a cable length of approximately 11,700km

The JUNO cable system introduces leading-edge SDM (Space Division Multiplexing) technology, enabling the provision of 20 fiber pairs (40 cores) per cable, compared with a maximum of 16 fiber pairs or 32 cores using conventional technology.

The JUNO cable system consists of the following segments: 

• Trunk between Minamiboso, Japan and Grover Beach, USA: 18 Tbps/FP (20FPs), 9,356 km
• Harbour Pointe branch: 18 Tbps/FP (14FPs), 1,450 km
• Shima branch: 18 Tbps/FP (14FPs), 904 km

The JUNO cable system will provide a system capacity of 360Tbps, the largest among all of the existing trans-pacific cable systems, followed by Google's Topaz cable system of 240Tbps over 16 fiber pairs, and Hawaiki Nui of 240Tbps and PLCN of 144Tbps.

The JUNO cable system will be owned and operated privately by Seren Juno Network Co., Ltd. (“Seren Juno”).

Established in July 2022, Seren Juno is a joint venture of NTT Ltd. Japan Corporation, Mitsui & Co., Ltd., PC Landing Corp, and JA Mitsui Leasing, Ltd..  Seren Juno is a company incorporated in Japan and a special purpose vehicle for design, construction, sales and operations of the JUNO trans-Pacific submarine cable system.

Seren Juno establishes a wholly owned subsidiary Seren Juno Network America, Inc. (Seren Juno America), a company incorporated in California, the United States, as JUNO's landing party in the United States.

Seren Juno America contracts with PC Landing Corp, the owner of Grover Beach CLS and Harbour Pointe CLS, to land the JUNO cable system at these cable landing stations.

NEC Corporation (NEC) announced on July 21, 2022 that it has been contracted by Seren Juno Network Co., Ltd. to build the JUNO Cable System. 

On May 30, 2025, Seren Juno announced that the JUNO cable system has officially achieved Point-of-Presence (PoP) to PoP Ready for Service (RFS) status. This includes the completion of terrestrial backhaul connectivity on both the Japanese and the U.S. sides, and provides seamless end-to-end connectivity to major PoPs in Tokyo , Osaka , Los Angeles , and San Jose.