Xiao Qi and Yu Lanyi's lost sister Yu Qingdie grew up in the same orphanage and had a deep relationship. When the Yu family finally found their lost daughter, Yu Qingdie, who had become mentally retarded, couldn't live without Xiao Qi, so Xiao Qi was taken back to the Yu family with her. Yu Lanyi gradually fell in love with this girl who was 8 years younger than him...