In addition, the Japanese investment giant will also pay $3 billion annually for the use of OpenAI technologies in SoftBank Group companies.
The joint venture, SB OpenAI Japan, will be owned by OpenAI and a company founded by SoftBank and its domestic telecommunications division.
By the way, last month's launch of the Stargate project was Sohn's second public appearance with Donald Trump after he was elected president in November.
Son's support of OpenAI signals his return to active investment after a period of cutbacks caused by the decline in the value of SoftBank's technology portfolio and a series of significant failures.
It has a long history of partnerships with tech companies in the U.S., including bringing the iPhone to Japan in 2008.