An encounter leads to deep love; a miss leads to ten years of waiting. She said to him: "The world under the sycamore tree belongs only to you and me. This is our secret." He believed it and treasured the space that belonged to them. When he saw her having close contact with another boy, his heart was hurt and he quietly left. On her birthday, he prepared a surprise for her and confessed her love to him. However, in their secret space, she was having an affair with someone else. His heart completely collapsed and he left angrily. In the year of graduation, she couldn't find him and sat alone under the plane tree, crying quietly. Ten years later, they met again, and he treated her coldly, no longer as gentle as before~~~~~~. The day before he and his girlfriend got engaged, she asked him to meet under the sycamore tree. She said: "The sycamore flowers bloomed, and I gave it to you as an engagement gift~~~~~~, a love that has never begun, an unforgettable love, who missed whom?