how do i use skill 6? "call lilith when chiho is around"
To use skill 6, you must:
1. Finish the story and game in onsen (hot spring), make her pregnant. (After the cutscene, you will be moved back to your apartment)
2. Call Chiho to your apartment, then
3. Choose the purple symbol with the horn, named: "Call Lilith", this symbol should be placed next the symbol "Spy-cam", then
Enjoy the scene!
If you do not have the purple symbol, it might be that you have not yet unlocked the story in onsen.
Hope this help.