_atoms-hoge.scss

$a-atom-setting: 1 !default;
@mixin a-label($var) {
  //attrs
  font-size: $var;
  @content;
}

_functions-fuga.scss

$f-function-setting: 1 !default;
@function color($var) {
  @return true;
}

_molecules-component.scss

$m-component-padding: 1rem !default;
%m-component {
  .inner {
    padding: $m-component-padding;
  }
  .element {
    background: #eee;
  }
  .p-index & .element {
    background: #aaa;
  }
}
.m-component { @extend %m-component; }

_organisms-organism.scss

%o-organisms {
  .component {
    @extend %m-component;
  }
}
.o-organisms { @extend %o-organisms; }

_pagas-page.scss

%p-index {
  padding: 1rem;
  .organisms {
    @extend %o-organisms;
    margin: 1rem;
  }
}
.p-index { @extend %p-index; }

style.scss

@import 'functions-fuga';
@import 'atoms-hoge';
@import 'molecules-component';
@import 'organisms-organism';
@import 'pagas-page';