One~san Day☆by☆Day

Main character lives alone and attends art lessons at a vocational school. One day a cousin suddenly arrives to help him around the house. Protagonist has a faint memory of a loving sister doing the house chores, so he reluctantly lets her in. But then four more girls arrive saying absolutely the same. Who of them is his real cousin from the past? His life turns in a mess while he tries to figure it out.

[From vndbreview]