Francis-Henri Graffard's four-year-old has enjoyed a fantastic campaign on European soil, belatedly breaking his Group One duck in the Grand Prix de Saint-Cloud before adding the King George VI And Queen Elizabeth Stakes and the Champion Stakes at Ascot to his burgeoning CV.
Carrying the colours of Aga Khan Studs, Calandagan was held up off the pace in Tokyo by Mickael Barzalona before charging up the home straight to mount his challenge and he got the better of a pulsating final furlong duel with hot favourite Masquerade Ball by a head.
The son of Gleneagles is the first horse trained outside Japan to win the country's showpiece event since Luca Cumani's Alkaased in 2005, while his victory was also achieved in a course record time.
Nemone Routh, manager for the Aga Khan Studs in France told the Press Association: "It was a fabulous race, unbelievable.
"I'm told it was not only a record time for the Japan Cup, but apparently it was the fastest mile and a half race ever run. Almond Eye (winner of the Japan Cup in 2018 and 2020) previously held the record for a mile and a half and apparently Calandagan has now lowered that record.
"There are no words really. It's a big ask coming over here as it's a 24-hour trip and you are taking them out of their routine, he's not being trained in the same way and this is where a lot of credit goes to his rider and Francis for being able to train him, even though you're not in the same training conditions, to be able to perform at this level in his last race of the year. It's phenomenal really.
"Francis has also broken the record for the number of Group One wins in a calendar year for a French-based trainer. He was level with Andre Fabre with 13 wins and now he's made it 14 with this win."
A tilt at the Japan Cup has been in the works for some time, with Routh adding: "We took this race very seriously. We kind of made a bit of a mental note after he won the Grand Prix de Saint-Cloud as we realised he had qualified for a bonus in this race.
"We wanted to do one big international race with him at the end of the year and we identified this as the race, which is why he didn't go to York for the Juddmonte International and he didn't go to the Irish Champion Stakes. We wanted to keep him fresh for the end of the year.
"The race we felt would be the best prep race for him was the Champion Stakes as he can't run in the Arc (due to being a gelding) and he's just responded to every call this year. Mickael has so much confidence in him and they're an amazing team."
Calandagan will now be given a well earned break before returning in search of more riches in 2026, when connections will also look forward to campaigning their Prix de l'Arc de Triomphe hero Daryz.
"We'll bring him home. He's obviously not going for the Hong Kong Vase. He is invited but that's only a couple of weeks away and we wouldn't do that to the horse as while he is a phenomenal athlete, he isn't a big, strong horse and you have to respect him," Routh continued.
"The Sheema Classic in Dubai probably has to be on the agenda, but we haven't made any firm plans.
"We've got Daryz to put in the equation as well, but I would imagine Calandagan will do a bit more international travelling, whereas Daryz will be kept to European Group Ones."