That year, when Qi was twelve years old, he gritted his teeth looking at the little girl who was a head taller than him, arrogant. That year, when Gong Sheng was thirteen, he was so angry that he gritted his teeth looking at the thin little boy. They are neighbors and enemies. Later, the two of them got on the same plane and went to a foreign country. On the plane, he leaned on her shoulder, and she left her heart with him. Later, after two years of separation, the two got back together. That year Gong Sheng was sixteen, looking at him who was a head taller than her, her heart was beating like thunder. That year, Qi Rong was sixteen, but when he looked at her, his heart felt completely calm. But, is this really the case? That year, is it called forgetting or remembering? Can Gong Sheng regain the sincerity of his childhood?