So there isn't a save system as far as I can tell, so exploring all options just means restarting a lot. I don't think every choice matters, but here's a short walkthrough for the _one_ sex scene I found:
- Collect both heart-fruits (beach+hut) (don't think its necessary but it just takes 2 clicks)
- Once you get to the town, talk to both girls, exhaust all options
- Go to alley on right side (arrow), talk to the two characters there, exhaust all options
- Enter another alley, towards hotel. You'll get jumped by black creatures. Click on one of the black creatures.
- Wake up, Gigi is there, now pick THESE options:
1. You're Gigi?
2. How long have I been out?
3. I mumble?
4. I know.
5. What do you have in mind?
This leads to a sex scene, afterwards you can join up with them, but I haven't found anything more, game seems to end around there.