For public relations specialist Mari Hirata, the perks that drew her into the world of freelancing were the flexible working hours and the opportunity to work for various companies.

When she started freelancing in 2011, Hirata had just given birth. But now that her kids are a little older, she has begun to increase her workload. She is currently working for four different startups as a public relations specialist.

"Being a freelancer allows you to control the amount of work you do. If you want to earn money, it's up to you to work as much as you want," Hirata, 34, said. "Some people can earn even more money after they become a freelancer."