In the autumn of 2000, eighteen-year-old A Niu saw Su Jiao for the first time in the classroom. He wrote a clumsy letter, and she gave him a paper ring in return, on which was written, "A hundred years without changing." Four years later, she returned the ring to him on the bleachers of the playground, saying, "I love you too much, so I have no way to watch you keep growing up not a day older." Eight years later, twenty-eight-year-old A Niu reunited with a married Su Jiao in a coffee shop. She placed the yellowed paper ring on the table once again and said, "This thing should have a destination." Four encounters, three returns, a youth spanning eight years—that clumsy, naive, and sincere twenty-year-old A Niu lives forever inside his body.