Guigui and Aaron have been best friends since they were eight. What if Guigui leaves Aaron when they're ten? Aaron, the ever so distant twin and opposite of Wangzi, has little faith in people and one of the few people he did trust left him without even saying goodbye.

What if Guigui returns after 8 years to spend her summer back in their hometown and discovers that Aaron changed so much that it would be hard to bring back their relationship?

Will the past matter when the present is more important? Or will their promise of watching the sunrise together in the 'city of romance' disappear in an instant?