Harem route so sweet 4 cute girls

Aoi's father remarries to a woman with 4 daughters, 2 sets of twins, the oldest girls, Aya and Shiori are the same age as Aoi. Three of the girls are emotionally attached to Aoi because he sepirelitly helped each of them in grade school. The girls wont to aim for a life together, but Aoi has to be convinced