Media playback is unsupported on your device Media caption The pizza chain that's a hit in Vietnam

While proud Italians might balk at some of the pizza toppings Yosuke Masuko offers, they'd have to appreciate his obsession with quality control.

The 38-year-old Japanese expat is the founder of one of the most popular pizza chains in Vietnam, Pizza 4Ps.

With six busy restaurants in the country's three largest cities - Ho Chi Minh City (formerly Saigon), Hanoi and Da Nang - it serves more than 3,000 customers every day.

They flock to the outlets to try such pizza delights as salmon miso cream, teriyaki chicken, and ginger fried pork.

With more traditional pizzas also available, such as margarita and Parma ham, such is Mr Masuko's attention to detail that when the first restaurant opened in Ho Chi Minh City in 2011, he would refuse to accept payment for any pizzas that weren't perfectly round.

And importing key ingredients from Italy, including the flour and tomato sauce, he worried that the imported Italian mozzarella wasn't fresh enough because of the long cargo flight, and the fact he could only get deliveries twice a week.

Image copyright Aaron Joel Santos Image caption Yosuke runs the business with his wife Sanae

So Mr Masuko decided he would make his own. As the cheese didn't exist in Vietnam he couldn't ask anyone locally for help, so instead he learned to make it himself by studying YouTube videos.

Then unhappy with the quality of milk he was able to buy in Vietnam, he bought a farm and his own cows.

Some might say this is a little too obsessive, but Mr Masuko says he wouldn't have it any other way.

"The mission of our restaurant is 'delivering wow, sharing happiness'," he says. "To pursue our mission we keep in mind to always go beyond customer expectations."

Image caption The company also sells more traditional, Italian-style pizzas

While neither the Japanese nor the Vietnamese are renowned for their pizza eating, Mr Masuko first started making them in 2004 when he installed a wood-fired pizza oven in his garden in Tokyo.

"The experience of making your own pizza with friends every weekend made me realise that I can make people happy by serving good food in a good space," he says.

However, it wasn't until seven years later that Mr Masuko decided to start making pizza for a living. By that time he was living in Vietnam where he worked for a Japanese investment firm.

Fascinated by Vietnam's rising middle class, he noticed that global pizza chains such as Pizza Hut and Domino's were opening up in the country and proving popular. As Vietnam had been a former French colony, the country was used to bread products, particularly baguettes, so pizza didn't prove too much of a jump for most people.

Image copyright Aaron Joel Santos Image caption The restaurants are popular among Vietnam's growing middle class

So with fond memories of his own pizza-making exploits Mr Masuko quit his job and used his $100,000 (£77,000) savings to open the first branch of Pizza 4Ps in central Ho Chi Minh City.

The 4Ps part of the unusual name stands "for peace". He explains: "In the name 4Ps is our wish for inner peace and richness of hearts."

Looking back, Mr Masuko says that quitting his investment job was not a decision he took lightly.

"Everything was fine with my previous job back then," he says. "The company even provided accommodation, and my eldest daughter was three when we opened the first restaurant.

"Of course I was afraid that the restaurant wasn't going to work, but at the same time I felt like I needed to take the challenge."

Image caption The restaurants are located in busy central locations

Thankfully for Mr Masuko his restaurant was an immediate hit, and the company has grown steadily ever since.

From 10 workers to begin with, it now has 700 full-time Vietnamese staff and 13 Japanese employees, five of whom have management roles.

Mr Masuko says that when the first restaurant opened, 90% of its customers were Japanese expats, 5% Vietnamese and 5% other foreign nationals.

Today more than 70% of diners are Vietnamese.

Image caption Pizza 4Ps also sells sweet, dessert pizzas

In addition to making its own cheese, Pizza 4Ps also arranges for Vietnamese farmers to grow it vegetables such as rocket and lettuces. The company also sells some of its cheese to hotels and other restaurants.

Mr Masuko says: "In 2016 we had a turnover of $7.5m, and in 2017 we expect $15m."

Ultimately the aim is to float the company on a stock exchange, and open branches in other countries.

To help run the business Mr Masuko relies on his wife Sanae, whom he met when they both worked for the same Japanese investment fund.

Image caption The business has both Vietnamese and Japanese staff

While Mr Masuko has the chief executive role, Sanae looks after staffing matters and marketing.

Rather than pick Japanese or Vietnamese as the working language at Pizza 4Ps, staff are instead encouraged to talk to each other in English.

Mr Masuko admits that this can occasionally cause communication problems, but says that cultural differences can sometimes be the biggest problem.

Sanae explains: "We found the gap of working culture between Vietnamese and Japanese is the one that is difficult to bridge... but things are improving."

Image caption Yosuke meditates every day before work

Hang Do, vice president of Seedcom, a Vietnamese investment fund, says she wasn't surprised that Pizza 4Ps has done so well.

"For the past five years, as the economy has grown, the middle class has grown very fast as well, and people have just been more open-minded to the diversity of food and beverages," she says. "Pizza 4Ps offers a very unique flavour."

Mr Masuko says he is confident that the Vietnamese pizza market will continue to grow, and he is putting in the hours to ensure that Pizza 4Ps continues to be a success.

"I go to the office at 9am, and I do work 13 hours a day. I am devoting my life to working."