Interesting concept.
I think the problem with the game is that there really isn't much replayability and basically you have to start over with each girl (at least after 3-4 sessions with each one I didn't play for too long) it gets monotonous too quickly.
I think after a few visits from the same girl the gameplay should change somehow... For example, a girl should not mind to start the massage naked after a few sessions with a happy ending, and among her requests "needs" maybe there should be some "delicate ones" and not just the standard legs, back, arms, etc.?
It would be nice to add more personality and preferences to the girls, more more dialogues, unique phrases and preference for certain actions over others...
To be honest, I would even prefer a little more slow burning so that the girls don't allow too much during the first session (let's say topless at most) and gradually increase the degree of what is allowed. Not too much, but a little more than now, when a girl can allow literally everything from the very first session. Maybe over time, as the player's reputation grows, it's worth adding the ability to promote your salon as a tantric massage and so that some mid-lategame girls start coming specifically for this from the very beginning (but to get to this point player need reputation, skill, etc.).
Good luck with the development, the game has good potential and the concept just in my opinion needs more personality so that the girls feel more alive