Kim Kardashian, Lewis Hamilton romance heats up during family holiday in Japan

Kim Kardashian and Lewis Hamilton are showing they're serious as she introduced him to her three children during their trip to Japan.

The duo, who were first reported by The Sun as dating earlier this year, were seen together in Tokyo just ahead of the Japanese Grand Prix next week.

The couple wasn't alone; Kim's three children - Saint, 10, Chicago, nine, and six-year-old Psalm - joined them during their spring break.

"It's more than just a fling. Kim doesn't easily get interested, but she’s definitely intrigued," an insider shared with People.

"He's a laid-back guy with upbeat vibes.

"Her family approves of him, and Kim is really taken by him. Both have demanding careers, but they make time to meet as often as possible."

Kim was also joined by her sister Khloe, 41, along with her children, True, seven, and Tatum, three.

The Skims founder has three children and daughter North, 12, with her ex-husband and musician, Kanye West, 48.

On Sunday, Kim and Lewis strolled through Tokyo's streets before being spotted by onlookers.

He gestured to onlookers who were eager to capture a photo.

While flanked by security, Kim K, 45, waved at spectators in a form-fitting grey dress.

Hand-in-hand with Hamilton, the American expressed affection for onlookers.

Frequently in the limelight, the power couple moved on from posing at last week’s Vanity Fair Oscars afterparty.

Seven-time Formula One World Champion Hamilton is readying for a race in just a few days.

He’s set to begin practice at the Suzuka Circuit on Thursday for the season’s third race.

Kim’s relationship with Lewis became public after The Sun disclosed she travelled from Los Angeles on her £100million private jet to spend an evening with him.

On January 31, the pair enjoyed a quick getaway at the exclusive Estelle Manor in the Cotswolds, with insiders noting they had the spa all to themselves, followed by a private dining experience.

A source informed The Sun: "It appeared quite romantic. Kim and Lewis explored all available amenities.

"She had two bodyguards for company and Lewis had a security officer, though they stayed in the background.

"Two of them stood guard outside their door, ensuring no disturbances."