Dokidoki Memories - NPC Sex in a Romance Game

In the world of a romance sim, violate the NPCs and heroine
in a way completely unrelated to the story.

Includes a usual romance game happy ending with the heroine.

[Outline]
A move to a new town. A fated meeting between a boy and a girl.
More than friends, but not quite lovers...
But forget about that, and go ahead and have your way with the characters...

[Elements]
Your little sister coming to love her brother
Your mother driven mad by sinful lusts
Pregnancy revelations
The purehearted heroine turned into a shameless slut

There is still a happy ending to aim for with the heroine, so try getting around to
that at least once...