When Swallows Return North

When the swallows return north, I will be back. This is your promise back then. Swallows have flown north and south countless times, and I have been taken away from my life during the swallows' north-south flight, but you still have not come back. In fact, swallows have never returned north. The swallows that flew south either stayed in the south or died in the south. The swallows that returned north were all new arrivals... Maybe Su Ho knows, maybe he doesn't know, maybe he is pretending not to know... Concept: The prosperity and troubled times of the Tang Dynasty