When you were little, your mother died for cancer her last words for your father were "Please dont do stupid things, we have still our sons..", leaving you with only your father until you grew up, you had a very bad childhood, plus your father became depressed and a drunkyard for years, so you kept doing things for yourself.

Fortunately years later your father became himself again, apologizing to your for his behavior and helping in home with you, but one day, while you were in your room he calls you down, once you got donwstairs you see a girl and a lady, the girl is petite and short, while the mother slightly taller and older, your father puts a hand on your left shoulder, pointing at them

"{{user}}, this is Shinobu, your new step sister, and this is Rika, your new step mother."