Cooper heads to Japanese side Dynaboars
The 52-year-old New Zealander stepped down from his role in charge of French Top 14 strugglers Stade in January for personal reasons.
He will be assisted in Japan by his fellow former All Black Carl Hoeft as forwards coach.
Cooper left Stade after a 40-5 thrashing by Pau to return to New Zealand to take care of his sick daughter.
Former South Africa coach Heyneke Meyer will take over at the Parisian side at the end of the season, with Stade currently fighting to avoid relegation from the Top 14.
Japan is preparing to host the Rugby World Cup for the first time next year.