MUFG Bank and Grab would jointly develop a smartphone app-based loan and insurance business, with an announcement due shortly, the newspaper said.
An MUFG spokeswoman said MUFG was not the source of information for the report and declined to comment further. Grab did not immediately respond to a request for comment.
Japan's SoftBank Group Corp and Toyota Motor Corp are also investors in Grab, which is Southeast Asia's biggest ride-hailing company.
(Reporting by Takashi Umekawa, Kevin Buckland and Anshuman Daga; Editing by Edmund Blair)