In the new crime flick “One Line,” Jin Goo transforms into Jang Seok-goo, a silver-tongued scammer who has a knack for sizing people up and persuading them accordingly.

In the film, which traces the story of a gang that helps people fabricate documents to obtain loans from banks, Jang squints at clients and scrutinizes their appearance while making a scanning gesture with his fingers.

“It’s the most relaxed I’ve been on set,” Jin told The Korea Herald during an interview Monday at a cafe in Palpan-dong, Seoul. “The character is the closest to my real self out of the ones I’ve played so far.”

That is not to say that the actor, a happily married family man who recently became a father of two sons, is deceptive by nature. “I’m a terrible liar,” he said. “Which is ironic, considering that it is my job to lie, you could say, on screen, and be someone that I’m not. But I do have a sharp eye for reading people.”

Jin made his debut in the 2003 “All In,” a drama about gambling starring Lee Byung-hun -- who to this day is a mentor to Jin. “He’s like a father to me,” Jin has said of Lee in the past. He has also long been with Lee’s management agency BH Entertainment.

Now 36, the actor has been mostly cast in strong, charismatic roles “because of my pronounced features, I guess,” he said.

He earned critical recognition through the 2009 film “Mother,” directed by Bong Joon-ho, who unearthed a raw “sexiness” in the actor, Jin has said. For his performance in “Mother,” Jin received prizes at the Grand Bell Awards and Blue Dragon Film Awards.

But only last year did the seasoned actor come into more widespread fame after starring in “Descendants of the Sun,” the military drama that enjoyed sensational popularity throughout Asia. Jin starred as the stoic but passionate Sgt. Seo Dae-young, alongside actor Song Joong-ki, and his romance with fellow officer Yoon Myung-joo, played by Kim Ji-won, gathered a following of enthralled fans.

Jin feels that his popularity is a short-lived one, a “bubble that will soon lose air.” 

Directly after “Descendants” aired, he was met with crowds of fans at airports when landing in Southeast Asian countries. It was the kind of fame Jin had dreamt of as a budding actor but had never experienced. He had long given up on it, concluding “it’s not for me” and pursuing projects that stoked his interest instead.

“I’m trying to enjoy every moment of it,” he said of his newfound fame. “My biggest concern is what project to move onto next.”

“I really enjoy giving interviews,” said the gregarious actor. “I just don’t like taking photos. I don’t know what to do when people look at me posing. That’s what I mean when I say I’m not a good liar.”

He’s also fun-loving. At home, he has a room devoted solely to board games and comic books; and when he reads a script, he has to be “entertained” in order to audition for it. “It has to read quickly and easily,” he said.

What Jin enjoys most about the filming process on set is the camaraderie that develops among the cast in between grueling hours. A keen drinker, Jin has recently developed a taste for wine. The topics of conversation with his drinking buddies are rarely serious ones.

“It’s mostly jokes and nonsense,” he said, laughing.

There was a time when Jin would overanalyze his characters before filming, but after over a decade in the business, he has concluded that his job is to act. The details of a character are something to “discuss closely with the director, who has a much better grasp of the story,” he said.

“I’ve found that the best things come when you’re open and relaxed.”

“One Line” hits local theaters Wednesday.

By Rumy Doo (doo@heraldcorp.com)