What is love? We've been asking for a thousand years. Everyone has a different answer. For the past two years, the heroine, Duo Xiaoxiao, has often felt a familiar, hazy sensation. She can't put it into words, share it with others, or discuss it with them. But now and then, that sensation slips into her heart, making her feel ethereal, transparent, and even breathless. Whenever she tries to grasp it, it cruelly slips away. Duo Xiaoxiao is often tormented by this feeling until she becomes hysterical. Yet whenever she despairs, it softly returns and encourages her. So, despite all the torment, Duo Xiaoxiao continues to seek love and strive to live her life. Eventually, her childhood sweetheart becomes the close companion she had always hoped for. But regret is an unavoidable part of life, and Duo Xiaoxiao is no exception. Just as happiness arrives, turbulent undercurrents are always poised to destroy what is beautiful. Years later, with remarkable calm, Duo Xiaoxiao writes a very, very long letter to the person she loves most. In it, she matter-of-factly describes how she gave everything she had to capture that familiar sensation and make peace with it. She is grateful for her sorrowful past. A lucid soul was always entangled with her, teaching her how to encounter the most beautiful love.