A Tokyo listing by Saudi Arabian Oil Co. would boost Japan’s effort to re-establish itself as a global financial center, but it could also highlight areas in which the country has laxer disclosure standards.

The number of foreign companies listed in Tokyo has fallen to five from more than 100 in the early 1990s as the nation’s economic clout has declined. Tokyo Gov. Yuriko Koike has been trying to get Tokyo back on a par with Asian financial hubs such as Singapore and Shanghai.

With...