Eve no Ringo

Kawai Kirika wants, more than anything else in the whole wide world, to be a manga artist. Her dream consumes her, drives her - she is *determined* to become a pro. So, when every shoujo manga company she visits rejects her work for being too adult, she takes a risk and goes to a shounen company. To her shock, they accept her...but on one condition. The magazine she's working for is an S&M manga magazine. The editor, an evil tick of a guy requires her to study up on BDSM and submit a story.

(Source: Mangaupdates.com)