Zume Pizza, a start-up that uses robots to make pizza, has reportedly received $375 million of backing from the tech investment firm SoftBank.

The California company announced the cash injection in a securities filing. The investor identity was not revealed in the filing, but the Wall Street Journal has been the first to report that the cash has come out of SoftBank's Vision Fund.

The Japanese bank's Vision Fund is worth $100 billion. It is most heavily backed by a $45 billion payment raised from Saudi Arabia's Public Investment Fund.

The WSJ report added that the SoftBank is expected to invest a further $375 million in the company, valuing the pizza delivery company at roughly $2.25 billion.