Donald has made 31 appearances for Bath, scoring over 150 points, since joining the Aviva Premiership side after the 2011 Rugby World Cup.
"I've had a great time with Bath, but feel it is time for a new challenge in a new league," he said.
"I'd like to thank everyone at the Club and all the Bath supporters for all the support during my time here, and I'm really looking forward to doing all I can to help us end this season on a high."
He will join an increasing cast of former Chiefs players in Japan with winger and one test All Black Lelia Masaga announcing last week his signing with the Honda club while centre Richard Kahui confirmed earlier in the year that he's signed with Toshiba.
All Black loose forward Adam Thomson has also signed a two year deal with the Canon Eagles.
Former All Blacks Mils Muliaina (NTT Docomo Red Hurricanes) and Jerome Kaino (Toyota) currently play in Japan while Brad Thorn, Ma'a Nonu and Sonny Bill Williams have all played there in the recent times.
Donald made 23 appearances for the All Blacks after making his test debut in 2008. His final act for New Zealand was kicking the winning penalty in the 2011 Rugby World Cup final against France.
- Herald Online
