Next question: how can I grind mystic without skills
You need to Learn from Rinny, first then to the second floor of the Succubus tower.
You need to go to the Library, talk to everyone, then after that Ask Rinny, to teach you.
After she has taught you the first Magic you get, go to the training Hall, and thats about it.
Resting Rooms, at the third floor if Lust,begins to tire out.
First has she interrupt you try to do Cassie, bathed together with Cassie, and placed dress-up with Cassie (swapping Cassie outfit over and over again until she stop you)
if you have after sleeping a day or two Cassie will set some rules for Alissa after that go around the abandoned town and find Alissa as a random encounter