So we have a former ganster/yankee father; plain but adorable mother; stylish OL or Uni student eldest sister; some weird gyaru with dreadlocks 2nd sister (what is with all this adopted talk that kind of fashion exists in Japan); presumably otaku 3rd sister and finally our other MC who seems to take after the father to form up a quite adorable and funky family.
And on the other corner we have a damn adorable looking best friend, I suppose. Is it just me or does she look a little like Kuroki?
Hope we will get to see more of the supporting characters in future chapters.