(CNN) When Ayumi Saito was 22 she broke up with her boyfriend.

But the Tokyo resident found an easy way to fill the void left by her ex lover's departure.

She downloaded a romance gaming app onto her phone, and became one of the millions of women in Japan to swap real life intimacy for a fantasy.

"I felt lonely," says Saito, now 31. "Japanese men are shy and not good at flattering women. But girls want to hear 'I love you'."

The virtual boyfriends she found in games like " Metro PD: Close To You " -- which sees a female detective discover a life-changing romance while fighting crime -- did all the things her former partner hadn't.

Women in Japan are finding love with virtual characters on their phones.

"When I was tired at the end of the day, before going to sleep, I was so relieved to hear his sweet and gentle words," she tells CNN.

Saito is by no means unusual.

In a society where 44.2% of women -- almost half of Japan's millennial singles aged between 18 and 34 -- are virgins, this industry has seemingly tapped into a deep desire for simulated intimacy in Japan.

The birth of romance gaming

Dating simulation apps first appeared in Japan in the 1980s. Known as "bishoujo" they would generally focus on a male protagonist pursuing pretty anime-style female characters.

In 1994, a team of female coders at Japanese gaming company Koei broke with tradition, launching the first romance game for women, "Angelique". Based on the quest of a blonde teenage girl, who is a candidate to be the next " Queen of the Universe ", to choose her perfect suitor, it was wildly successful.

Japanese businesswoman Nanako Higashi and her husband, Yuzi Tsutani, saw a niche in this lucrative sector. Japan has the second largest mobile gaming market in the world, generating $6.5 billion of sales in 2016, according to the Global Games Market Report

So, in the mid-2000s the duo pivoted their punk gaming business, Voltage , to cater to the female audience, debuting their first dating app for women "My Lover is The No.1 Host" in 2006.

"Almost all women are under stress," says Higashi. "We wanted to provide something for them."

That proved to be an excellent business strategy.

Today, Voltage is a world leader in female romance simulation apps, catering to female "otaku" -- intense fans of popular culture, such as anime and manga -- and other curious women.

It offers 88 romance titles, says its games have been played by 50 million (mostly female) users globally and, in the year leading up to June 2016, the company made ¥11.2 billion ($102 million), having also released English versions of some of its apps in the United States and Europe.

"It doesn't matter what your type of male would be, you'll find a man that you'll really like (in these games)," says Kukhee Choo, assistant professor of comparative culture at Sophia University, in Tokyo.

"And, of course, that male is going to be perfect.

"The perfect boyfriend."

Twelve samurai suitors

More of a "choose your own path" manga novel than a typical mobile phone game like Candy Crush, for example, (all romance apps are presented as stories, in chapters), it immerses the user in the war-torn Sengoku Era (1467 to 1603), where the waitress protagonist has to runaway to save her brother's life, and conveniently meets 12 potential samurai suitors along the way.

Photos: Japanese women play the game of love: Voltage's best apps Era of Samurai Code of Love – Voltage's romance game "Era of Samurai Code of Love" takes players back to the world of Shinsengumi warriors, where a slew of swordsmen vie to steal their heart. Hide Caption 1 of 15 Photos: Japanese women play the game of love: Voltage's best apps Sakura Amidst Chaos – Taking place at a time of deep unrest in Japan, "Sakura Amidst Chaos" combines danger, love and heroic warriors. As the warlords vie for power, you're courted by various with strong samurai suitors who show their softer sides. Hide Caption 2 of 15 Photos: Japanese women play the game of love: Voltage's best apps The Sleepless Cinderella – A gossip reporter in Tokyo attends a casino opening party, mingling with VIPs. The next morning, she wakes up alone in a hotel room -- half naked. Hide Caption 3 of 15 Photos: Japanese women play the game of love: Voltage's best apps Enchanted in the Moonlight – Supernatural powers and human lust are the key concepts in "Enchanted in the Moonlight". Hide Caption 4 of 15 Photos: Japanese women play the game of love: Voltage's best apps Gangsters in Love – Dangerous gangsters make for irresistible romantic flings in "Gangsters in Love". Hide Caption 5 of 15 Photos: Japanese women play the game of love: Voltage's best apps Kiss Me On Clover Hill – This takes place at Tokyo's National University of Fine Arts and Music, in a fictitious house called Clover Hill -- that just so happens to be full of attractive male students. Hide Caption 6 of 15 Photos: Japanese women play the game of love: Voltage's best apps Kissed by the Baddest Bidder – At a black-market auction VIP artists, rich and famous models, and Hong Kong triad members are read to splurge. Due to a series of unfortunate events, the gamer -- a hotel housekeeper -- lands herself among the auction prizes. Hide Caption 7 of 15 Photos: Japanese women play the game of love: Voltage's best apps Liar! Uncover the Truth – The main character dumps her cheating boyfriend only to find herself surrounded by 10 new love interests -- but nine of them are liars. Trusting no one, she sets out to uncover the truth. Hide Caption 8 of 15 Photos: Japanese women play the game of love: Voltage's best apps My Wedding and Seven Rings – An ordinary office worker unexpectedly inherits a successful company when her grandfather, the CEO, passes away. She starts getting proposals from all the ambitious men in her office, but must determine true love from blind ambition. Hide Caption 9 of 15 Photos: Japanese women play the game of love: Voltage's best apps Our Two Bedroom Story – The main character moves into a new house after her mother gets engaged. Owned by her future stepfather, the house already has a renter -- your new stepbrother, who also happens to be a co-worker. A romance unfolds, complicating both your family relationships and career. Hide Caption 10 of 15 Photos: Japanese women play the game of love: Voltage's best apps My Forged Wedding – This is one of Voltage's earlier games -- and one of the most popular. The main character moves to Tokyo and enters into a fake marriage as a favor to a friend. But things get complicated when she ends up falling in love with her faux beau. Hide Caption 11 of 15 Photos: Japanese women play the game of love: Voltage's best apps Castaway! Love's Adventure – Stranded on a tropical island, gamers struggle to focus on survival when there are so many romantic distractions. Hide Caption 12 of 15 Photos: Japanese women play the game of love: Voltage's best apps Butler Until Midnight – An ordinary young woman learns she is actually the daughter of a prestigious Japanese family. She moves into her real family's luxurious home, and falls in loves with her father's butlers. Hide Caption 13 of 15 Photos: Japanese women play the game of love: Voltage's best apps Astoria Fate's Kiss – It's all myths and monsters in this epic love saga by Voltage, where the main character explores potential relationships with Greek demigods who need her help. Hide Caption 14 of 15 Photos: Japanese women play the game of love: Voltage's best apps After School Affairs – An all-girls school and an all-boys school merge, and suddenly life gets much more interesting for the teachers who find their new colleagues irresistible. Hide Caption 15 of 15

"What's unique about the female romance genre is that there are so many men in each game," says Choo, noting that few female characters aside from the protagonist are introduced.

Several times per chapter, the user must choose from a list of "love tactics" detailing how she could interact with these men, the goal being to achieve greater intimacy with the preferred samurai -- who normally sends mixed signals to keep the heroine keen.

"The strong and selfish men are the most popular," says Higashi. "The most popular characters are strong on the outside and only sometimes sweet for you."

In Japan this type of suitor is called the "tsundere" -- literally: "hot-cold" -- man. For North America audiences, Voltage tweaks the formula, as it says women there want a "macho man, both mentally and physically".

When love makes money

Broadly speaking, there are two business models for the romance apps.

The "novel" genre works on a fremium model, meaning they are free to download, but after reading the "prologue" users must pay about $4 to $5 to download the subsequent 13 or so chapters.

Paying for the epilogue often brings an extra layer of romance: simulated sex scenes are a common feature.

You'll find a man that you'll really like ... and, of course, that male is going to be the perfect boyfriend Kukhee Choo, assistant professor of comparative culture

The "party" games, meanwhile, give away five or so chapters free per day, but users must pay extra to advance in the story, and to purchase add-ons such as clothes and make-up that will make them more attractive to their suitors.

There are other extras, too.

"You actually can receive an email from your love in some games," says Higashi. "It'll say, 'Don't forget the date tomorrow night', and if you register your with name, he'll include that, too."

Sweet fantasy?

While other countries also have a romance gaming app culture -- in the United States, for example, gaming producer Cheritz is a leader in the market -- the craze has taken off in Japan at an unprecedented pace.

Choo believes the industry's success is down to underlying social issues.

"As a society as a whole, there is a sense of alienation in the urban setting," she tells CNN. "A lot of people feel they're not connected to their peers."

A government survey released in 2015 in Japan found that nearly 40% of single people in their 20s and 30s did not want a romantic partner, in real life at least.

Yuirka, 26 -- who asked CNN not to use her full name -- lives in Tokyo and began playing romance games when she turned 20.

She is currently single in real life.

"These romance games make me feel I want to be in love with someone," she tells CNN. "The boys in these games have something lacking in the real life boys -- they are so sweet."

Does she worry spending her time living out romantic fantasies means the real thing won't live up to expectations?

"I know that it is a game," she says. "A boyfriend in a romance game cannot be a substitute for a real boyfriend."

Physical transformation

Choo, however, believes the fantasy being sold in romance games is shaping some girls' expectations in real life, especially in "host clubs" -- bars and cafes where men are employed to lavish attention on female customers.

"For the host club men, it's their job to be consumed by women," says Choo. "Some of these female players go to host clubs and order hosts like they're playing a game. They will choose males likes characters."

Choo believes there is a "physical transformation" taking in place in these clubs, as men working there try to look "closer to 2D characters", who are typically drawn as boy band-esqe "pretty boys".

For now, at least, there are no official statistics to prove a direct correlation between using such games and being single, or that romance games are steering the image of Japanese men.

Higashi says that with more of Japanese society opting for life alone, and shunning intimacy, romance gaming could be a harmless substitute.

"It is true some of our users are probably scared to be in love in real life and enjoy the virtual romance," she says.

"I think our desire to love and be loved by someone is universal. We'll continue to provide a good service for the women who want such a feeling around the world."