Seiichiro Umeno is a partner at Nagashima Ohno & Tsunematsu. He handles a wide variety of corporate transactions, such as M&A and administration of general shareholders' meetings. He also specializes in dispute resolution, including litigation and preliminary injunction procedures. His practice especially focuses on defense against hostile takeovers and dispute resolution in connection with M&A transactions.

He graduated with a B.A. in politics from Waseda University in 1985 and with an LL.M. from the University of Pennsylvania Law School in 1993. He was also a lecturer at the Legal Training and Research Institute of the Supreme Court of Japan from 2005 to 2008.