Controversy erupted last month when HappyPlayTime, a crowdfunded app that uses games to teach women about genital anatomy and masturbation techniques, was rejected by Apple's App Store due to its inappropriate "erotic and mature themes."

The app aims to "eliminate the stigma around women's masturbation," according to its official website. HappyPlayTime creator Tina Gong writes on the app's blog that her team's mission is to see "more women be vocal about their sexuality - in particular, about masturbation."

Much like the app, women's masturbation is a taboo subject in China. But that hasn't prevented HappyPlayTime generating interest and support among some Chinese women.

"We are waiting for the Android version of the app," said Xiao Yue, a local feminist who made headlines in March after marching from Beijing to Guangzhou, Guangdong Province, to raise awareness about sexual assault in China. "I was surprised [it was banned] because I thought Apple was an open-minded company. This allows us to see clearly which gender lacks sexual freedom."

As a conservative country, China has long grappled with how to effectively teach sex education. But as the door gradually opens and awareness increases, topics once off-limits like women's masturbation are being discussed and even encouraged by social activists and scholars.