The company Tokyo Metro was incorporated in 2004, adopting its heart-shaped "M" logo in place of the network's previous one: a spiky, space-age "S" for subway.

Tokyo Metro will aim to raise 320 billion yen ($2.23 billion) - making it the largest IPO in Japan for six years - while Rigaku, the Carlyle Group-backed maker of X-ray testing tools, is targeting ...