This is not a visual novel per se, but the choices you can make are just stylistic. You always have clear tasks that you have to do, but you have often multiple progressing simultaneously, so you have some freedom how you want to go through things.
Based on what you just wrote this game is as far from your expectations as it can get:
- limited freedom of action
- the role play is restricted to sex, but no RPG elements
- shopping is minimal, you can only buy a couple of items
- there is a rather nice hotel upgrade system for a visual novel, but don't expect complex skill trees
- controlling sex and eroticism... I am not sure what you mean. You have some sexual control over the women, but the sex scenes are mostly given and you are limited in what you can do.
- and lastly, sandbox. Let's just say that this game has a higher chance including my wife as a character than being a sandbox game
Grüß Gott von Österreich mein Freund. Wie geht es dir da drüben?