The whole family goes on a self-driving road trip. The twin older brother and older sister bring a cat and a dog, while the mother arranges for the youngest daughter, Yuyu, to sit in the back row by the window. Along the way, she holds a small electric fan, quietly looks out the window, and occasionally turns back to listen to her family talking. During a rest stop, the family discovers that she has fallen asleep and will not wake up no matter how much they call her. Only later does everyone slowly realize that this child, usually the most sensible one, kept many words locked deep inside her heart. A story about "being sensible" and "being seen".