The new deal at Ricoh will initially be for one season, with an option for another year. Ellison could, therefore, possibly come back and play for the Highlanders again.
Money was obviously a factor in the decision to move on, he said. His brother, prop Jacob, was also playing in Japan, for the Sanix club.
Ellison, who has come back from a lengthy shoulder injury, said he was a professional rugby player, whose last job before rugby was a milk run.
"When you are 30, like I am, and you have a couple of kids, you have to take a reasonably balanced approach to a decision."
He had loved his time with the All Blacks, playing four tests for the national side, although he wished he had played more against the top-ranked nations.
"Had I started this year all guns blazing, who knows whether I would have stayed. But I didn't. I was out for six months and played my third game last week. And that is a couple of months ahead of schedule."
He did not expect to be named in the All Black squad for the tests against France.
