Taiwan Docs

The 28-day cycle in lunar calendar is used to measure female reproductive cycle. The “taboo of menstrual cycle” derived from the primal fear for blood. As a result, menstrual cycle is often regarded as something filthy. The film uses close-up shots to expose the issue and change the barrier that lies between the (open) public and the (self-contained) private spaces.

Source: Taiwan Women's Film Association
http://www.wmw.com.tw/en/data_content.php?Imovie_id=592