Incoming Celtic manager Ange Postecoglou Friday said he had "created something special" with Japan's Yokohama F. Marinos but couldn't turn down a "tremendous opportunity" with the Scottish giants.
The former Australia boss was named Celtic manager on Thursday, replacing Neil Lennon who resigned in February.
The 55-year-old Australian's appointment has been met with bemusement in some quarters, with Celtic fans rushing to find out more about a manager who is virtually unknown in Europe.
Postecoglou guided Australia to their first ever Asian Cup title in 2015, and has won domestic championships in Japan and his home country.
He won the J-League with Marinos in 2019 after moving to Japan the previous year, and he said he was satisfied with his achievements after signing off on Friday.
"We created something special at the football club. I constantly speak to them about creating a bit of a legacy for themselves," Postecoglou told an online press conference.
"I made a decision. It was a difficult decision because I've loved my time here, but it was a tremendous opportunity before me and I'll have plenty of time to talk about that," he added.
Marinos won the Japanese title playing high-tempo, aggressive football, finishing six points clear of their nearest rivals in 2019. They finished ninth in 2020.
"When I began here, I had a vision of how I wanted the club to not just play football, but be perceived from outside by other people," Postecoglou said.
"People who watch Marinos now know what to expect in terms of our football, know that we won't change our approach, that we believe in something as a football club. I think that was the most important thing for me."
In Scotland, Postecoglou will be tasked with restoring Celtic's supremacy over Rangers who, under Liverpool great Steven Gerrard, won the title 25 points clear of their bitter Glasgow rivals.
But the Australian is confident he has the credentials to deliver, having led Marinos to their first league title in 15 years.
"It hasn't been easy for the players, because I've challenged them to play a certain way which is very difficult," he said.
"But every one of them have just wanted to learn, wanted to improve, were prepared to take risks knowing that if mistakes were made, I would take responsibility."
Postecoglou's appointment ends a long-running saga for Celtic, who were keen to hire former Bournemouth manager Eddie Howe.
However, talks broke down with the Englishman in late May.
Postecoglou will arrive with Celtic in full transition.
Chief executive Peter Lawwell is standing down after almost two decades, and captain Scott Brown leaving after 14 years for a player-coaching role at Aberdeen.