Fake business cards, impostors at meetings and forged documents stamped with the company seal are behind what appears to be an elaborate scam that Lehman Brothers in Japan alleges bilked it of millions of dollars in vanished investment money.

The alleged fraud is at the center of a $350 million lawsuit Lehman Brothers Holdings Inc. filed Monday in Tokyo, which has ensnared one of the biggest names in Japan’s road to modernization and economic power — trading house Marubeni Corp.