Tsubomi-chan, Wasuremono Nai?

A girl named Tsubomi tends to fall asleep when attempting to act properly. After dozing off in a park, she wakes to find herself in the care of an elderly man called Grandpa. He takes her to meet the Ariake family, a group of individuals who defy conventional norms—featuring a male mother, a female father, and an older brother named Yuki-chan, who has been largely ignored. Tsubomi becomes part of this unconventional, makeshift family, taking on the role of their younger sister.