You need to:
- Have Ayumi's corruption to be 10 or higher.
- Give either her or Soushi a low grade on the previous weekly tests.
- Have Sharing enabled by telling the President that you will share the girls.
- When Ayumi asks what to do, you need to manipulate her a bit and tell her to repay Soushi some other way. (Comply with Soushi). This option only appears if you have sharing enabled, otherwise it's hidden.