Going househunting with the rich and famous can be a tricky business. The American pop diva Mariah Carey “doesn’t do stairs”. Paris Hilton won’t look at property without a walk-in refrigerator, “where I can chill out”.

And then there is Yuki Oshima-Wilpon.

Like Miss Hilton, Yuki, 24, is a darling of New York high society. Her father, a Korean-Japanese entrepreneur, is worth $1.4 billion (£795m), according to Forbes magazine, the American business bible. She is married to Bruce Wilpon, 27, son of Fred Wilpon, the New York multimillionaire real-estate developer who also owns the New York Mets baseball team. They recently left New York for London because they want to establish themselves out of the shadow of their parents.

The golden couple are trying to raise their profile and launch themselves into London society, which is why I find myself at Farnborough private airport on a cold winter’s day. Yuki wants to buy a home in the hills above Monaco and has invited The Sunday Times to join her, to see her in action and to hear her “strong views” on animal welfare.

Yuki does not “fly commercial”. Her Club 328 private jet is waiting on the tarred apron, and the pilot is growing fidgety. Yuki is late. Very late. Twenty minutes before we are due to take off, her car finally arrives and she rushes into the terminal, her Dior earrings and matching watch jangling. “I really need to pee!” she shrieks, and rushes to the lavatory. Five minutes pass. Then another five. And another five.

“Is she okay?” I ask her husband, who is beginning to look embarrassed. “Oh, she’s always like this,” Bruce smiles. Yuki finally emerges, freshly made-up. “I want to look right. Can you Photoshop out my love handles?” she asks The Sunday Times’s photographer.

Crossing the French coast a few minutes later at 30,000ft, Yuki disappears into the lavatory again. This time she takes 20 minutes, and we are descending fast towards the Côte d’Azur by the time she emerges. Sensing that I am suspicious about why she is taking so long, she comes, er, clean.

“I like to wash my hands all the time,” she says. “I like to clean the toilet and put paper on it and stuff. Cleanliness is definitely one thing. There’s not, like, a rational explanation.”

Waiting for Yuki at Nice airport are Wendy MacAnthony and her team, from international property firm, MacAnthony Realty International.

On her way to view the first property, Yuki explains what she looks for in a house. She is a Buddhist, whose homes must have perfect “placement” and perfect feng shui. Walls should be white inside and out, and there must be a “sense of fluidity and continuity between the spaces”. Leather and fur products are strictly off-limits. The garden must be certified pesticide-free, with organic plants. Energy must be provided by solar panels and the pool naturally cleaned with marine salts, not chlorine.

When she arrives at the 230sq m (2,475sq ft) modern villa in a gated community near Beaulieu-sur-Mer, Yuki asks to see the bathroom, and once it is spotlessly clean she completes the tour of the house. She hates it. The kitchen is a “joke” and the lawn is too green. “It’s pesticides.” The place has “no soul”. Nul points.

Back on the road to the next property, the blue BMW Yuki is travelling in heads down a steep hill. This, she says, breaks the rules of feng shui: “You should not live on a descending hill”. The modern glass and steel house meets her hygiene standards, but the view is too ugly — it looks out over the flat roof of a neighbouring apartment block.

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