Simpson Thacher & Bartlett is representing Kohlberg Kravis Roberts & Co. on a $1.3 billion acquisition of Japanese conglomerate Hitachi Ltd.’s power tools manufacturing unit.

Hitachi announced in December that it was considering selling a non-core business, such as Hitachi Koki, in order to focus on its main businesses, which include facilities and equipment for the oil and gas industry and public transportation. Tokyo-listed Hitachi Koki makes power tools and equipment for home and industry use.