For the past six years, Mr. Chen, a Taiwanese home-appliance salesman, has been living a double life. For one thing, Chen isn't his real surname – he adopts the pseudonym Xiao Chen, or Little Chen, on weekends. For another, in his downtime he forgoes casual attire such as jeans and T-shirts, and instead dresses up as his favorite female cartoon character.

Like more than 120,000 people in Taiwan and millions around the world, Mr. Chen, 25, is a passionate fan of cosplay – a contraction of "costume" and "play" – a growing subculture that originated in Japan. Participants use elaborate makeup and clothes to role-play characters and objects from cartoons, comic books and videogames.

"I'm not ashamed of my hobby," said Mr. Chen at a cosplay gathering at Taipei Main Station plaza this month, though he added that "my family would probably disown me if they ever found out." Around six foot tall and bulky, he was sporting a blue maid costume inspired by the central character in "Magical Girl Madoka of the Magus," his favorite Japanese anime series.

"I know there are many negative conceptions of cosplay, but for me, it's a stress reliever," he said. "Cosplay allows me to be the real me after a week of pretending to be the person that the society expects me to be."

Another cosplayer at the event, a 17-year-old high school student who goes by the alias Penguin, said that dressing up like the wise man Ja'far from her favorite Japanese manga series "Magi - Labyrinth of Magic," made her feel "powerful" – albeit only for few hours. Fearful of crowds and often labeled as a loner, the self-described introvert said she now has no problem striking poses for anyone who wants to take her picture.