They say don't mix business with pleasure, but actress Jo Yoon-hee has gotten pretty close in the upcoming TV series "Pied Piper."

Jo, who plays the sympathetic crisis negotiator Yeo Myeong-ha, has partnered with actor Shin Ha-kyun, her former crush.

"Acting with (Shin) has been amazing. Personally, he used to be my ideal man," Jo told a news conference discussing the tvN police thriller on Thursday. "I was excited and honored just to be able to work with him. He didn't disappoint."

Asked around when she had been infatuated with Shin, she replied, "ten years ago," prompting laughter among the crowd.

In the series that will succeed tvN romantic comedy "Cheese in the Trap," Ju Seong-chan (Shin) is a corporate negotiator-turned-policeman who has seemingly mastered the art of persuasion. He strives to resolve crises through communication rather than force.

While Jo may have had ulterior motives for joining the program, Shin says he was mostly drawn to the show's novelty.

"I chose this show because the story offers plenty of excitement and conveys a clear message," he said, adding "negotiation" is a topic rarely dealt in TV series. "All negotiations start from communication and understanding between people. That's something our society should value more."

Another character in the mix is Yun Hui-seong (Yu Jun-sang), an anchorman primarily concerned with TV ratings and would forgo the truth to sensationalize stories.

Behind all terrorist attacks and hostage crises is a mysterious man, known as "Pied Piper," and his identity will be revealed slowly.

Like Shin, Yu says he appreciates the fact that this show is different.

"I like that this show raises questions about our society," he said. "I hope the show provides an opportunity for us to contemplate on past incidents and discuss them."

To get the facts straight, "Pied Piper" producers completed crisis negotiation courses offered by the New York Police Department and the Federal Bureau of Investigation in the U.S. and have sought advice from professor Lee Jong-hwa at the Korean National Police Agency since 2011.

The entire main cast sat through a special lecture on crisis negotiation with Lee, and Yu was personally coached by star anchorwoman Baek Ji-yeon to play the role.

Much of the credit for choosing negotiations as the theme goes to little-heralded writer Ryu Yong-jae, who wrote the screenplay for tvN's TV adaptation of the Japanese manga, "The Liar Game."

"There hasn't been any show exploring the topic of negotiation in Korea," he said, adding he was inspired by the 1998 Hollywood movie "The Negotiator." "Professor Lee, a trailblazer for that field in Korea, has given many interesting examples of crisis negotiation and that has helped tremendously with writing this show."

Ryu says if the series tops 5 percent in viewership, he wants to return the favor by providing uniforms created for "Pied Piper" to all the crisis negotiators in Korea.

"Despite being short on budget, they have helped our show. I want the uniform myself because it's pretty," he said.

It's unusual for a screenwriter to make that kind of pledge, which has traditionally been made by actors and actresses.

Producer Kim Hong-sun says he wants to give a voice to a minority group in society.

"It's common for us to equate negotiating with giving-and-taking," he said. "I started this drama to hear out those who have nothing to give. You'd think they can't be negotiated with, but I'll show why communicating with them is still important."

The 16-part series premieres on March 7 at 11 p.m. (Yonhap)