Kohlberg, Kravis, Roberts and Permira are vying to acquire Citigroup-owned BellSystem24, Japan’s largest telemarketer, in a deal that would be one of the largest private equity investments in Japan this year.

Nikko Principal Investments, an investment company wholly owned by Citi’s Japan unit, is looking to sell BellSystem24, which it acquired for about Y150bn ($1.5bn) in 2004.