Movies featuring animals as the main characters are often CGI-heavy. But director Son Jae-gon chose instead to make actors wear animal masks and outfits in the upcoming movie “Secret Zoo.”

Two other animal comedy movies will hit theaters here in January -- South Korean film “Mr. Zoo” and “Dolittle” featuring Robert Downey Jr. However, Son expects the meticulously designed animal costumes and the chemistry between the animal and human characters to differentiate “Secret Zoo” from the other films.

Based on a webcomic, “Secret Zoo” -- whose Korean title translates to “We Don’t Hurt (You)” -- revolves around the story of a trainee lawyer from a major law firm, Tae-soo, who is appointed as the head of Dongsan Park, a near bankrupt zoo, and put in charge of revitalizing it.

Almost all the animals at the zoo, especially the big ones that people usually come to see, are sold to pay off debt, and Tae-soo plans an extraordinary project to “imitate” the animals.

Along with Tae-soo, four employees of Dongsan Park -- a former zoo manager, a veterinarian and two zookeepers -- go behind bars and inside cages to fool the zoo’s visitors.

Ahn Jae-hong plays Tae-soo and a cola-drinking polar bear in the movie.

“It was fun, especially because I played the animal that I personally like and we made the film in winter. Acting wearing the suits in summer may have been a different story,” Ahn said Monday after the movie’s press screening in Seoul. The actor played Jung-bong in the popular tvN series “Reply 1988” and a main role in JTBC’s “Melo Is My Nature.”

Meanwhile, Kang So-ra, who plays zoo veterinarian So-won and a lion, said she looked up various sources to study animal movements.

Known for her upright, strong female characters -- such as in the movie “Sunny” (2011) and hit tvN drama “Misaeng” (2014) -- Kang plays a courageous veterinarian doing whatever she can to save an old and sick polar bear, Black Nose, whom she had befriended since young.

The movie also cast veteran actor Park Yeong-gyu as the former zoo manager and a bodiless giraffe, actor Kim Sung-oh as a zookeeper and a gorilla, and actress Jeon Yeo-been as the other zookeeper and a giant sloth.

Director Son, who specializes in comedy, is returning to the big screen nearly 10 years after his last piece, “Villain and Widow” (2010).

Son debuted as a director in 2006 with “My Scary Girl” and is recognized for creating a unique genre incorporating romantic, comedy, and thriller elements.

“Secret Zoo” opens in local theaters on Jan. 15.

By Choi Ji-won (jwc@heraldcorp.com)