Wahei Hinata is a 28-year-old employee at Aida House, a company aiming to bring their customers desired houses. With his father setting out on a personal journey, Wahei finally leaves his old, inadequate house and starts living in a newly built apartment. While on his way home, he bumps into a trio of sisters: 16-year-old Hotaka Kunimae and 7-year-old twin sisters China and Chise.

As it turns out, the three girls are actually Wahei's sisters from a different mother. Due to them having no place to return, Wahei's father pushes the three on his son's shoulders. As he spends more and more time with these new family members, Wahei comes to learn one hard truth: although architecture may build a house, it is memories and family that create a home.