According to Business Insider, WeWork, the fast-growing office leasing startup, has raised $300 million from Japan's SoftBank and could rake in a total investment of $3 billion in a massive funding round.

The deal could be among the first from SoftBank's $100 billion technology Vision Fund, which was announced last October and is being described as the largest fund of its kind in the world.

WeWork has just received an investment of $300 million from SoftBank itself, according to the Wall Street Journal. The company is expected to raise a further $2.7 billion from SoftBank's Vision Fund.

Private investors currently value WeWork's business at $17 billion, and the latest investment round is likely to propel WeWork's valuation even higher, the WSJ said.

WeWork and SoftBank declined to comment.

Back in January, it was reported that SoftBank's Vision Fund was mulling a $1 billion investment in WeWork. At that time, the Wall Street Journal reported that some SoftBank executives were concerned about investing in a startup with such a rich valuation, especially a real estate startup that some see as far afield from the Vision Fund's tech focus.

The Vision Fund is made up of contributions from SoftBank itself, Saudi Arabia via the Kingdom's Public Investment Fund, and other investors from around the world, including Oracle Executive Chairman Larry Ellison and Apple.