Tomorrow

Although it had been stated that Kim Shin was 939 years old, as he is explaining his punishment to Ji Eun Tak, he states that he's been serving this punishment for 900 years. This means he was 39 years old when he died as a human and 23 when he began protecting the young king. (The young king was 17 when Kim Shin died and 37 when he himself died as he was in a crypt when Kim Shin was revived 20 years later)

Although it's shown that if Kim Shin is sad or depressed it rains and or gets cloudy, when he and Ji Eun Tak are both crying and sad, it is clearly shown to be sunny outside.