SAN FRANCISCO — The plaintiffs lawyers that once secured the largest-ever award in a gender discrimination suit from a Cravath, Swaine & Moore client have a new target: Japanese pharmaceutical firm Daiichi Sankyo.

In a complaint filed Monday in the Northern District of California, six women represented by the employment law boutique Sanford Heisler accuse Daiichi Sankyo Co. of underpaying female sales reps, failing to promote them along with male colleagues, and discriminating against pregnant employees and working mothers.