Kisaragi Sumi is a 20-year-old university student. But do not be surprised that she is a 65-year-old inside. Under pressure to help out with the family business from a young age, she could not have a youth. Even afterwards, she devoted her entire life to taking care of first her grandmother and then her father and mother. Sumi finds herself turning 65 without ever having had a boyfriend. She takes a little pride in having lived with integrity. But after her mother passes away, she has the sudden thought of regaining her youth once more and making a fresh start in life. A miracle happens to her. One day when Sumi wakes up, she has the appearance of a 20-year-old! Despite being bewildered by this unbelievable reality, she introduces herself as Sumire and gets another try at youth.