Simpson Thacher & Bartlett (STB) and Mori Hamada & Matsumoto have advised U.S. buyout firm KKR & Co in its acquisition of Nissan Motor-backed auto parts maker Calsonic Kansei Corp for up to 498.3 billion yen ($4.5 billion). 

Nissan was represented by Anderson Mori & Tomotsune, while Nagashima Ohno & Tsunematsu advised Calsonic Kansei.

This is KKR’s biggest deal in Japan. In 2013, it purchased Panasonic Healthcare from Panasonic Corp for $1.67 billion, and acquired Pioneer DJ from Pioneer Corp in 2014 for $550 million.

The Simpson Thacher team was led by partner David Sneider.