Karen is a brave woman who has mastered the power of light.

Although she was from a commoner, she defeated many monsters and made her
name roar from the royal capital to the remote villages . For some reason, the power of light doesn't work, and I'm fighting back ... I'm the only one who survives. However, despite feeling helpless, she did not give up and asked for help from the scientist "Eris" who is said to be a wise man. What was presented there was to abandon the power of light once and change the class to darkness. After increasing the power of darkness-the power of indecentness- to aim for a hidden class with both the power of light and darkness . However, it was a dangerous road with the risk of becoming a so-called "dark fall" in this world and falling into a lewd act. -Can Karen defeat the Demon King as a noble hero without falling ? Or will he fall without a shadow and become famous as a horny hero ...?