Ouyang Guannan (played by Shi Ya) and Shi Tujie (played by Benjamin Hung) are a pair of common campus lovers. They both love photography and have the same competitive personality. They are attracted to each other but always use bickering as a way to get along. Although they quarrel constantly, the love between the two young boys is still growing secretly. They leave an appointment under the rainbow in the back mountain, but they miss their fate due to a misunderstanding at graduation. Four years later, the two reunited at the anniversary celebration and became lovers. When they were sweet, Ah Jie broke the appointment and planted the seeds of disaster. When they met again, they were already different. Ah Nan and Ah Jie, although separated by Yin and Yang, could still see each other, but in the eyes of others, Ah Nan had become a lunatic who muttered to himself. After constant quarrels with his father (played by Hui Shaoxiong), and with his senior brother (played by Carlos Chan) always silently caring for him, Ah Nan finally had to face the fact that Ah Jie was no longer in the world...