Ospreys lock Davies was called up by head coach Warren Gatland after Cory Hill had to return home after failing to recover from a leg fracture.
It meant two-time World Cup star Davies – who is 32 and has 65 caps – was forced into a quick departure for the Far East.
“I was pretty rushed last week to be fair. I was preparing for a game at the Ospreys and then I had to jump on a plane and leave my family behind,” he said.
“It was difficult at the time, but the coaches have looked after me really well. They’ve drip-fed me into training. I’m pretty good now.
“I had a missed call from Gats. I called him back and he said ‘Can you jump on a plane tomorrow?’ I went home, kissed my wife and kids goodbye, and was straight in the car.”
Davies added: “Cory is a good mate of mine and I’ve grown up with him. He was in the academy when I was at Cardiff Blues and I always looked after him.
“Cory is a good guy and he’ll come back from this. It’s obviously disappointing, but I guess he’ll have another few World Cups to worry about.
“I just kept fit and hoped the call would come.”
Wales’ players and management are enjoying four days off in Otsu after the team claimed a dramatic 29-25 win over Australia.
Davies has always been one of Wales’ most charismatic characters and he gave an insight into how the 2019 camp are getting on at the World Cup.
“I’ve been around the squad a long time so I’ve got a place at the back of the bus just heckling people, that’s my role,” he laughed.
“Joke of the day is on fire at the moment. Leigh Halfpenny, Jake Ball and Owen Watkin are in that department.
“At the moment it’s James Davies and Liam Williams on entertainment and they’ve been pretty good to be fair. Dan Biggar is always in charge of laundry.
“The massive thing that I will probably miss after rugby is the camaraderie and coming to training every day. It’s always underpinned by how hard we train on the field.
“Once we cross that white line, we train harder than anybody.”
Liam Williams and some of Wales’ players went fishing on Ōtsu’s Lake Biwa on Tuesday.
There was also a lake cruise for the squad that evening, as part of a unique welcoming ceremony from the city (watch the video here).
Davies said: “I came to Japan with Wales in 2013. We stayed in Osaka and Tokyo.
“It’s a good place. The people are amazing with he way they look after you and they’re so polite. We pride ourselves on having good manners, but this is different level here.
“It’s just a joy to be here and experience different cultures. As rugby players we get a chance to go to these parts of the world. I’m from Beddau, so I didn’t really go on holidays much as a kid.
“Porthcawl was the furthest I went. Sometimes it’s hard not to just lie in your bed because you’re tired but you’ve got to get out there and experience stuff.
“I want to play as much as possible and compete for a place now I’m here.”
