The map is opened with the tab key (only available in the overworld).
The sex scenes are enabled by raising the relationship points with the girls.
When they are available they are notified in the quest log.
The scenes are normally only activated in Shura's apartment or Akemi's house.
Tamaho's scene is optional and appears in the side quest “Collecting Rent” in Gyon city.
The Shura first bath scene occurs in Shura's apartment and is activated by going to the bathroom door.
I hope this helped you.