I've just been dragging 3 npc girls along with me because I want gifts from them, in addition to having cute girls following me around and popping up on screen. Do these npc's give better gifts as their relationships increase, give presents more often, more client orders, etc? I noticed you get titles and they are a lot more friendlier talking to you when you see them on the ship.
Not gonna lie, it's nice when you're on the way to see the concert and Aki cheerfully says hi to you. Risa still best girl though.