I unlocked 4 skills
69 : Receive handjob from sister in bathroom when bathing together. Choose to clean yourself first, then choose clean hair and body. if your sister have good relationship and high interest, she will give you handjob. Then will give you inspiration. If not, try 2-3 times
Piledriver : When your sister sick, do not take care of her, instead choose Bath, and wipe her body. If you dont get it the first time, still don't take care of your sister, instead try it the next day when her condition should be still sick. Got it on my 2nd try
Doggy style : Read Naught book to get inspiration. (I don't know if this is chance or not, got it on my first book)
Titty fuck : Read Thin book, bought it at bookstore in town. You can visit it on weekend